Error analysis for the Global Positioning System
The analysis of errors computed using the Global Positioning System is important for understanding how GPS works, for knowing what magnitude of errors should be expected. The Global Positioning System makes corrections for receiver clock errors and other effects but there are still residual errors which are not corrected; the Global Positioning System was created by the United States Department of Defense in the 1970s. It has come to be used for navigation both by the U. S. military and the general public. GPS receiver position is computed based on data received from the satellites. Errors depend on the sources listed in the table below. User equivalent range errors are shown in the table. There is a numerical error with an estimated value, σ n u m, of about 1 meter; the standard deviations, σ R, for the coarse/acquisition and precise codes are shown in the table. These standard deviations are computed by taking the square root of the sum of the squares of the individual components. To get the standard deviation of receiver position estimate, these range errors must be multiplied by the appropriate dilution of precision terms and RSS'ed with the numerical error.
Electronics errors are one of several accuracy-degrading effects outlined in the table above. When taken together, autonomous civilian GPS horizontal position fixes are accurate to about 15 meters; these effects reduce the more precise P code's accuracy. However, the advancement of technology means that in the present, civilian GPS fixes under a clear view of the sky are on average accurate to about 5 meters horizontally; the term user equivalent range error refers to the error of a component in the distance from receiver to a satellite. These UERE errors are given as ± errors thereby implying that they are zero mean errors; these UERE errors are therefore used in computing standard deviations. The standard deviation of the error in receiver position, σ r c, is computed by multiplying PDOP by σ R, the standard deviation of the user equivalent range errors. Σ R is computed by taking the square root of the sum of the squares of the individual component standard deviations. PDOP is computed as a function of satellite positions.
A detailed description of how to calculate PDOP is given in the section, geometric dilution of precision computation. Σ R for the C/A code is given by: 3 σ R = 3 2 + 5 2 + 2.5 2 + 2 2 + 1 2 + 0.5 2 m = 6.7 m The standard deviation of the error in estimated receiver position σ r c, again for the C/A code is given by: σ r c = P D O P 2 × σ R 2 + σ n u m 2 = P D O P 2 × 2.2 2 + 1 2 m The error diagram on the left shows the inter relationship of indicated receiver position, true receiver position, the intersection of the four sphere surfaces. The position calculated by a GPS receiver requires the current time, the position of the satellite and the measured delay of the received signal; the position accuracy is dependent on the satellite position and signal delay. To measure the delay, the receiver compares the bit sequence received from the satellite with an internally generated version. By comparing the rising and trailing edges of the bit transitions, modern electronics can measure signal offset to within about one percent of a bit pulse width, 0.01 × 300, 000, 000 m / s, or 10 nanoseconds for the C/A code.
Since GPS signals propagate at the speed of light, this represents an error of about 3 meters. This component of position accuracy can be improved by a factor of 10 using the higher-chiprate P signal. Assuming the same one percent of bit pulse width accuracy, the high-frequency P signal results in an accuracy of
South Australia is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of 983,482 square kilometres, it is the fourth-largest of Australia's states and territories by area, fifth largest by population, it has a total of 1.7 million people, its population is the second most centralised in Australia, after Western Australia, with more than 77 percent of South Australians living in the capital, Adelaide, or its environs. Other population centres in the state are small. South Australia shares borders with all of the other mainland states, with the Northern Territory; the state comprises less than 8 percent of the Australian population and ranks fifth in population among the six states and two territories. The majority of its people reside in greater Metropolitan Adelaide. Most of the remainder are settled in fertile areas along River Murray; the state's colonial origins are unique in Australia as a settled, planned British province, rather than as a convict settlement.
Colonial government commenced on 28 December 1836, when the members of the council were sworn in near the Old Gum Tree. As with the rest of the continent, the region had been long occupied by Aboriginal peoples, who were organised into numerous tribes and languages; the South Australian Company established a temporary settlement at Kingscote, Kangaroo Island, on 26 July 1836, five months before Adelaide was founded. The guiding principle behind settlement was that of systematic colonisation, a theory espoused by Edward Gibbon Wakefield, employed by the New Zealand Company; the goal was to establish the province as a centre of civilisation for free immigrants, promising civil liberties and religious tolerance. Although its history is marked by economic hardship, South Australia has remained politically innovative and culturally vibrant. Today, it is known for numerous cultural festivals; the state's economy is dominated by the agricultural and mining industries. Evidence of human activity in South Australia dates back as far as 20,000 years, with flint mining activity and rock art in the Koonalda Cave on the Nullarbor Plain.
In addition wooden spears and tools were made in an area now covered in peat bog in the South East. Kangaroo Island was inhabited; the first recorded European sighting of the South Australian coast was in 1627 when the Dutch ship the Gulden Zeepaert, captained by François Thijssen and mapped a section of the coastline as far east as the Nuyts Archipelago. Thijssen named the whole of the country eastward of the Leeuwin "Nuyts Land", after a distinguished passenger on board; the coastline of South Australia was first mapped by Matthew Flinders and Nicolas Baudin in 1802, excepting the inlet named the Port Adelaide River, first discovered in 1831 by Captain Collet Barker and accurately charted in 1836–37 by Colonel William Light, leader of the South Australian Colonization Commissioners"First Expedition' and first Surveyor-General of South Australia. The land which now forms the state of South Australia was claimed for Britain in 1788 as part of the colony of New South Wales. Although the new colony included two-thirds of the continent, early settlements were all on the eastern coast and only a few intrepid explorers ventured this far west.
It took more than forty years before any serious proposal to establish settlements in the south-western portion of New South Wales were put forward. On 15 August 1834, the British Parliament passed the South Australia Act 1834, which empowered His Majesty to erect and establish a province or provinces in southern Australia; the act stated that the land between 132° and 141° east longitude and from 26° south latitude to the southern ocean would be allotted to the colony, it would be convict-free. In contrast to the rest of Australia, terra nullius did not apply to the new province; the Letters Patent, which used the enabling provisions of the South Australia Act 1834 to fix the boundaries of the Province of South Australia, provided that "nothing in those our Letters Patent shall affect or be construed to affect the rights of any Aboriginal Natives of the said Province to the actual occupation and enjoyment in their own Persons or in the Persons of their Descendants of any Lands therein now occupied or enjoyed by such Natives."
Although the patent guaranteed land rights under force of law for the indigenous inhabitants it was ignored by the South Australian Company authorities and squatters. Survey was required before settlement of the province, the Colonization Commissioners for South Australia appointed William Light as the leader of its'First Expedition', tasked with examining 1500 miles of the South Australian coastline and selecting the best site for the capital, with planning and surveying the site of the city into one-acre Town Sections and its surrounds into 134-acre Country Sections. Eager to commence the establishment of their whale and seal fisheries, the South Australian Company sought, obtained, the Commissioners' permission to send Company ships to South Australia, in advance of the surveys and ahead of the Commissioners' colonists; the Company's settlement of seven vessels and 636 people was temporarily made at Kingscote on Kangaroo Island, until
In software engineering, structured analysis and structured design are methods for analyzing business requirements and developing specifications for converting practices into computer programs, hardware configurations, related manual procedures. Structured analysis and design techniques are fundamental tools of systems analysis, they developed from classical systems analysis of the 1970s. Structured analysis is still in use today. Structured analysis consists of interpreting the system concept into data and control terminology represented by data flow diagrams; the flow of data and control from bubble to the data store to bubble can be difficult to track and the number of bubbles can increase. One approach is to first define events from the outside world that require the system to react assign a bubble to that event. Bubbles that need to interact are connected until the system is defined. Bubbles are grouped into higher level bubbles to decrease complexity. Data dictionaries are needed to describe the data and command flows, a process specification is needed to capture the transaction/transformation information.
SA and SD are displayed with structure charts, data flow diagrams and data model diagrams, of which there were many variations, including those developed by Tom DeMarco, Ken Orr, Larry Constantine, Vaughn Frick, Ed Yourdon, Steven Ward, Peter Chen, others. These techniques were combined in various published system development methodologies, including structured systems analysis and design method, profitable information by design, Nastec structured analysis & design, SDM/70 and the Spectrum structured system development methodology. Structured analysis is part of a series of structured methods that "represent a collection of analysis and programming techniques that were developed in response to the problems facing the software world from the 1960s to the 1980s. In this timeframe most commercial programming was done in Cobol and Fortran C and BASIC. There was little guidance on "good" design and programming techniques, there were no standard techniques for documenting requirements and designs.
Systems were getting larger and more complex, the information system development became harder and harder to do so."As a way to help manage large and complex software, the following structured methods emerged since the end of the 1960s: Structured programming in circa 1967 with Edsger Dijkstra - "Go To Statement Considered Harmful" Niklaus Wirth Stepwise design in 1971 Nassi–Shneiderman diagram in 1972 Warnier/Orr diagram in 1974 - "Logical Construction of Programs" HIPO in 1974 - IBM Hierarchy input-process-output Structured design around 1975 with Larry Constantine, Ed Yourdon and Wayne Stevens. Jackson structured programming in circa 1975 developed by Michael A. Jackson Structured analysis in circa 1978 with Tom DeMarco, Gane & Sarson, McMenamin & Palmer. Structured analysis and design technique developed by Douglas T. Ross Yourdon structured method developed by Edward Yourdon. Structured analysis and system specification published in 1979 by Tom DeMarco. Structured systems analysis and design method first presented in 1983 developed by the UK Office of Government Commerce.
IDEF0 based on SADT, developed by Douglas T. Ross in 1985. Hatley-Pirbhai modeling, defined in "Strategies for Real-Time System Specification" by Derek J. Hatley and Imtiaz A. Pirbhai in 1988. Information popularised by James Martin. According to Hay "information engineering was a logical extension of the structured techniques that were developed during the 1970's. Structured programming led to structured design; these techniques were characterized by their use of diagrams: structure charts for structured design, data flow diagrams for structured analysis, both to aid in communication between users and developers, to improve the analyst's and the designer's discipline. During the 1980's, tools began to appear which both automated the drawing of the diagrams, kept track of the things drawn in a data dictionary". After the example of computer-aided design and computer-aided manufacturing, the use of these tools was named computer-aided software engineering. Structured analysis creates a hierarchy employing a single abstraction mechanism.
The structured analysis method can employ IDEF, is process driven, starts with a purpose and a viewpoint. This method identifies the overall function and iteratively divides functions into smaller functions, preserving inputs, outputs and mechanisms necessary to optimize processes. Known as a functional decomposition approach, it focuses on cohesion within functions and coupling between functions leading to structured data; the functional decomposition of the structured method describes the process without delineating system behavior and dictates system structure in the form of required functions. The method identifies outputs as related to the activities. One reason for the popularity of structured analysis is its intuitive ability to communicate high-level processes and concepts, whether in single system or enterprise levels. Discovering how objects might support functions for commercially prevalent object-oriented development is unclear. In contrast to IDEF, the UML is interface driven with multiple abstraction mechanisms useful in describing service-oriented architectures.
Structured analysis views a system from the perspective of the data flowing through it. The function of the system is described by processes. Structured analysis takes ad
Sarajevo is the capital and largest city of Bosnia and Herzegovina, with a population of 275,524 in its administrative limits. The Sarajevo metropolitan area, including Sarajevo Canton, East Sarajevo and nearby municipalities, is home to 555,210 inhabitants.a Nestled within the greater Sarajevo valley of Bosnia, it is surrounded by the Dinaric Alps and situated along the Miljacka River in the heart of the Balkans. Sarajevo is the political and cultural center of Bosnia and Herzegovina, a prominent center of culture in the Balkans, with its region-wide influence in entertainment, media and the arts. Due to its long and rich history of religious and cultural diversity, Sarajevo is sometimes called the "Jerusalem of Europe" or "Jerusalem of the Balkans", it is one of only a few major European cities which have a mosque, Catholic church, Orthodox church and synagogue in the same neighborhood. A regional center in education, the city is home to the Balkans first institution of tertiary education in the form of an Islamic polytechnic called the Saraybosna Osmanlı Medrese, today part of the University of Sarajevo.
Although settlement in the area stretches back to prehistoric times, the modern city arose as an Ottoman stronghold in the 15th century. Sarajevo has attracted international attention several times throughout its history. In 1885, Sarajevo was the first city in Europe and the second city in the world to have a full-time electric tram network running through the city, following San Francisco. In 1914, it was the site of the assassination of Archduke Franz Ferdinand of Austria by local Young Bosnia activist Gavrilo Princip that sparked World War I, which ended Austro-Hungarian rule in Bosnia and resulted in the creation of the Kingdom of Yugoslavia. After World War II, the establishment of the Socialist Republic of Bosnia and Herzegovina within the Second Yugoslavia led to a massive expansion of Sarajevo, the constituent republic's capital, which culminated with the hosting of the 1984 Winter Olympics marking a prosperous era for the city. However, after the start of the Yugoslav Wars, for 1,425 days, from April 1992 to February 1996, the city suffered the longest siege of a capital city in the history of modern warfare, during the Bosnian War and the breakup of Yugoslavia.
Sarajevo has been undergoing post-war reconstruction, is the fastest growing city in Bosnia and Herzegovina. The travel guide series Lonely Planet has named Sarajevo as the 43rd best city in the world, in December 2009 listed Sarajevo as one of the top ten cities to visit in 2010. In 2011, Sarajevo was nominated to be the European Capital of Culture in 2014 and will be hosting the European Youth Olympic Festival in 2019; the earliest known name for the large central Bosnian region of today's Sarajevo is Vrhbosna. The name Sarajevo derives from the Turkish noun saray, meaning "palace" or "mansion"; the letter "j" in the Bosnian language is equivalent soundwise to the English letter "y" as in "boy" and "yet". The evo portion may come from the term saray ovası first recorded in 1455, meaning "the plains around the palace" or "palace plains". However, in his Dictionary of Turkish loanwords, Abdulah Škaljić maintains that the "evo" ending is more to have come from the widespread Slavic suffix "evo" used to indicate place names, than from the Turkish ending "ova", as proposed by some.
The first mention of name Sarajevo was in 1507 letter written by Feriz Beg. The official name during the 400-year Ottoman period was Saraybosna, it is still known by that name in modern Turkish. Sarajevo has had many nicknames; the earliest is Šeher, the term Isa-Beg Ishaković used to describe the town he was going to build. It is a Turkish word meaning an advanced city of key importance which in turn comes from Persian: شهر shahr; as Sarajevo developed, numerous nicknames came from comparisons to other cities in the Islamic world, i.e. "Damascus of the North". The most popular of these was "European Jerusalem"; some argue that a more correct translation of saray is government house. Sarajevo is near the geometric center of the triangular-shaped Bosnia-Herzegovina and within the historical region of Bosnia proper, it is situated 518 meters above sea level and lies in the Sarajevo valley, in the middle of the Dinaric Alps. The valley itself once formed a vast expanse of greenery, but gave way to urban expansion and development in the post-World War II era.
The city is surrounded by forested hills and five major mountains. The highest of the surrounding peaks is Treskavica at 2,088 meters Bjelašnica mountain at 2,067 meters, Jahorina at 1,913 meters, Trebević at 1,627 meters, with 1,502 meters Igman being the shortest; the last four are known as the Olympic Mountains of Sarajevo. The city itself has its fair share of hilly terrain, as evidenced by the many steeply inclined streets and residences perched on the hillsides; the Miljacka river is one of the city's chief geographic features. It flows through the city from east through the center of Sarajevo to west part of city where meets up with the Bosna river. Miljacka river is "The Sarajevo River", with its source 2 kilometres south of the town of Pale at the foothills of Mount Jahorina, several kilometers to the east of Sarajevo center; the Bosna's source, Vrelo Bosne near Ilidža, is another notable natural landmark and a popular destination for Sarajevans and other tourists. Several smaller rivers and streams such as Koševski Potok run through the city and its vicinity.
Sanskrit is a language of ancient India with a history going back about 3,500 years. It is the primary liturgical language of Hinduism and the predominant language of most works of Hindu philosophy as well as some of the principal texts of Buddhism and Jainism. Sanskrit, in its variants and numerous dialects, was the lingua franca of ancient and medieval India. In the early 1st millennium CE, along with Buddhism and Hinduism, Sanskrit migrated to Southeast Asia, parts of East Asia and Central Asia, emerging as a language of high culture and of local ruling elites in these regions. Sanskrit is an Old Indo-Aryan language; as one of the oldest documented members of the Indo-European family of languages, Sanskrit holds a prominent position in Indo-European studies. It is related to Greek and Latin, as well as Hittite, Old Avestan and many other extinct languages with historical significance to Europe, West Asia, Central Asia, South Asia, it traces its linguistic ancestry to the Proto-Indo-Aryan language, Proto-Indo-Iranian and the Proto-Indo-European languages.
Sanskrit is traceable to the 2nd millennium BCE in a form known as the Vedic Sanskrit, with the Rigveda as the earliest known composition. A more refined and standardized grammatical form called the Classical Sanskrit emerged in mid-1st millennium BCE with the Aṣṭādhyāyī treatise of Pāṇini. Sanskrit, though not Classical Sanskrit, is the root language of many Prakrit languages. Examples include numerous modern daughter Northern Indian subcontinental languages such as Hindi, Bengali and Nepali; the body of Sanskrit literature encompasses a rich tradition of philosophical and religious texts, as well as poetry, drama, scientific and other texts. In the ancient era, Sanskrit compositions were orally transmitted by methods of memorisation of exceptional complexity and fidelity; the earliest known inscriptions in Sanskrit are from the 1st-century BCE, such as the few discovered in Ayodhya and Ghosundi-Hathibada. Sanskrit texts dated to the 1st millennium CE were written in the Brahmi script, the Nāgarī script, the historic South Indian scripts and their derivative scripts.
Sanskrit is one of the 22 languages listed in the Eighth Schedule of the Constitution of India. It continues to be used as a ceremonial and ritual language in Hinduism and some Buddhist practices such as hymns and chants; the Sanskrit verbal adjective sáṃskṛta- is a compound word consisting of sam and krta-. It connotes a work, "well prepared and perfect, sacred". According to Biderman, the perfection contextually being referred to in the etymological origins of the word is its tonal qualities, rather than semantic. Sound and oral transmission were valued quality in ancient India, its sages refined the alphabet, the structure of words and its exacting grammar into a "collection of sounds, a kind of sublime musical mold", states Biderman, as an integral language they called Sanskrit. From late Vedic period onwards, state Annette Wilke and Oliver Moebus, resonating sound and its musical foundations attracted an "exceptionally large amount of linguistic and religious literature" in India; the sound was visualized as "pervading all creation", another representation of the world itself, the "mysterious magnum" of the Hindu thought.
The search for perfection in thought and of salvation was one of the dimensions of sacred sound, the common thread to weave all ideas and inspirations became the quest for what the ancient Indians believed to be a perfect language, the "phonocentric episteme" of Sanskrit. Sanskrit as a language competed with numerous less exact vernacular Indian languages called Prakritic languages; the term prakrta means "original, normal, artless", states Franklin Southworth. The relationship between Prakrit and Sanskrit is found in the Indian texts dated to the 1st millennium CE. Patanjali acknowledged that Prakrit is the first language, one instinctively adopted by every child with all its imperfections and leads to the problems of interpretation and misunderstanding; the purifying structure of the Sanskrit language removes these imperfections. The early Sanskrit grammarian Dandin states, for example, that much in the Prakrit languages is etymologically rooted in Sanskrit but involve "loss of sounds" and corruptions that result from a "disregard of the grammar".
Dandin acknowledged that there are words and confusing structures in Prakrit that thrive independent of Sanskrit. This view is found in the writing of the author of the ancient Natyasastra text; the early Jain scholar Namisadhu acknowledged the difference, but disagreed that the Prakrit language was a corruption of Sanskrit. Namisadhu stated that the Prakrit language was the purvam and they came to women and children, that Sanskrit was a refinement of the Prakrit through a "purification by grammar". Sanskrit belongs to the Indo-European family of languages, it is one of the three ancient documented languages that arose from a common root language now referred to as the Proto-Indo-European language: Vedic Sanskrit. Mycenaean Greek and Ancient Greek. Mycenaean Greek is the older recorded form of Greek, but the limited material that has survived has a ambiguous writing system. More important to Indo-European studies is Ancient Greek, documented extensively beginning with the two Homeric poems. Hittite.
This is the earliest-recorded of all Indo-European languages, distinguishable into Old Hittite, Middle Hittite and Neo-Hittite. I
The Salvation Army
The Salvation Army is a Protestant Christian church and an international charitable organisation. The organisation reports a worldwide membership of over 1.7 million, consisting of soldiers and adherents collectively known as Salvationists. Its founders sought to bring salvation to the poor and hungry by meeting both their "physical and spiritual needs", it is present in 131 countries, running charity shops, operating shelters for the homeless and disaster relief and humanitarian aid to developing countries. The theology of the Salvation Army is derived from that of Methodism, although it is distinctive in institution and practice. A peculiarity of the Army is that it gives its clergy titles of military ranks, such as "lieutenant" or "major", it does not celebrate the rite of Holy Communion. However, the Army's doctrine is otherwise typical of holiness churches in the Wesleyan-Arminian tradition; the Army's purposes are "the advancement of the Christian religion... of education, the relief of poverty, other charitable objects beneficial to society or the community of mankind as a whole".
The Army was founded in 1865 in London by one-time Methodist circuit-preacher William Booth and his wife Catherine as the East London Christian Mission, can trace its origins to the Blind Beggar tavern. In 1878 Booth reorganised the mission, becoming its first General and introducing the military structure, retained as a matter of tradition, its highest priority is its Christian principles. The current international leader of The Salvation Army and chief executive officer is General Brian Peddle, elected by the High Council of The Salvation Army on 3 August 2018; the Salvation Army refers to its ministers as "officers". When acting in their official duties, they can be recognized by the colour-coded epaulettes on their white uniform dress shirts; the epaulettes has the letters. Officers ranks include lieutenant, major and the general. Promotion in rank up to the rank from lieutenant to major depends on years of service; the ordination of women is permitted in the Salvation Army. Salvation Army officers were allowed to marry only other officers.
Husbands and wives share the same rank and have the same or similar assignments. Such officer-couples are assigned together to act as co-pastors and administer corps, Adult Rehabilitation Centers and such; as of 2016 the organisation will not appoint homosexual people to posts as ministers, preferring individuals "whose values are consistent with the church's philosophy". See LGBT clergy in Christianity; the Army has churches located throughout the world. They are known as Salvation Army corps, they may be implemented as part of a larger community center. Traditionally many corps buildings are alternatively called citadels; the Salvation Army is well known for its network of thrift stores or charity shops, colloquially referred to as "the Sally Ann" in Canada and "Salvos Stores" in Australia, which raise money for its rehabilitation programs by selling donated used items such as clothing and toys. Clothing collected by Salvation Army stores that are not sold on location are sold wholesale on the global second hand clothing market.
The Salvation Army's fundraising shops in the United Kingdom participate in the UK government's Work Programme, a workfare programme where benefit claimants must work for no compensation for 20 to 40 hours per week over periods that can be as long as 6 months. When items are bought at the Salvation Army thrift stores, part of the proceeds go towards The Salvation Army's emergency reliefs efforts and programs. Items not sold are recycled and turned into other items such as carpets and rugs, instead of being thrown away in landfills; the Salvation Army helps their employees by hiring ex-felons depending on the circumstances because they believe in giving people second chances. There are many job opportunities available for them nationwide and are able to move their way up to become a manager or work in one of their corporate offices; some shops are associated with an Adult Rehabilitation Centers where men and women make a 6-month rehabilitation commitment to live and work at the ARC residence.
They are unpaid. Many ARCs are male-only; the program is to combat addiction. They work at the store or residence; this is referred to as "work therapy". They attend twelve-step programs and chapel services as a part of their rehabilitation; the Army advertises these programs on their collection trucks with the slogan "Doing the Most Good". The general design pattern is that an ARC is associated with warehouse. Donations are consolidated from other stores and donation sites and sorted and priced and distributed back out to the branch stores. Low-quality donated items are sold at the warehouse dock in a "dock sale". Farmland at Hadleigh in Essex was acquired in 1891 to provide training for men referred from Salvation Army shelters, it featured market gardens and two brickfields. It was mentioned in the Royal Commission report of 1909 appointed to consider Poor Laws. 7,000 trainees had passed through its doors by 1912 with more than 60% subsequently finding employment. It has a Twitter feed @SalArmyHFE and website.
The Salvation Army operates summer camps for children, Silvercrest Residences, adult day care centers. It has headquarter offices internationally and for each territory and division; some of the other facilities include: Homele
Saudi Arabia the Kingdom of Saudi Arabia, is a country in Western Asia constituting the bulk of the Arabian Peninsula. With a land area of 2,150,000 km2, Saudi Arabia is geographically the largest sovereign state in the Middle East, the second-largest in the Arab world, the fifth-largest in Asia, the 12th-largest in the world. Saudi Arabia is bordered by Jordan and Iraq to the north, Kuwait to the northeast, Qatar and the United Arab Emirates to the east, Oman to the southeast and Yemen to the south, it is the only nation with both a Red Sea coast and a Persian Gulf coast, most of its terrain consists of arid desert and mountains. As of October 2018, the Saudi economy was the largest in the Middle East and the 18th largest in the world. Saudi Arabia enjoys one of the world's youngest populations; the territory that now constitutes Saudi Arabia was the site of several ancient cultures and civilizations. The prehistory of Saudi Arabia shows some of the earliest traces of human activity in the world.
The world's second-largest religion, emerged in modern-day Saudi Arabia. In the early 7th century, the Islamic prophet Muhammad united the population of Arabia and created a single Islamic religious polity. Following his death in 632, his followers expanded the territory under Muslim rule beyond Arabia, conquering huge and unprecedented swathes of territory in a matter of decades. Arab dynasties originating from modern-day Saudi Arabia founded the Rashidun, Umayyad and Fatimid caliphates as well as numerous other dynasties in Asia and Europe; the area of modern-day Saudi Arabia consisted of four distinct regions: Hejaz and parts of Eastern Arabia and Southern Arabia. The Kingdom of Saudi Arabia was founded in 1932 by Ibn Saud, he united the four regions into a single state through a series of conquests beginning in 1902 with the capture of Riyadh, the ancestral home of his family, the House of Saud. Saudi Arabia has since been a totalitarian absolute monarchy a hereditary dictatorship governed along Islamist lines.
The ultraconservative Wahhabi religious movement within Sunni Islam has been called "the predominant feature of Saudi culture", with its global spread financed by the oil and gas trade. Saudi Arabia is sometimes called "the Land of the Two Holy Mosques" in reference to Al-Masjid al-Haram and Al-Masjid an-Nabawi, the two holiest places in Islam; the state's official language is Arabic. Petroleum was discovered on 3 March 1938 and followed up by several other finds in the Eastern Province. Saudi Arabia has since become the world's second largest oil producer and the world's largest largest oil exporter, controlling the world's second largest oil reserves and the sixth largest gas reserves; the kingdom is categorized as a World Bank high-income economy with a high Human Development Index and is the only Arab country to be part of the G-20 major economies. The state has attracted criticism for a multitude of reasons including but not limited to: its archaic treatment of women, its excessive and extrajudicial use of capital punishment, state-sponsored discrimination against religious minorities and atheists, its role in the Yemeni Civil War, sponsorship of Islamic terrorists, its strict interpretation of Sharia Law.
An autocratic monarchy, the kingdom has the world's third-highest military expenditure and, according to SIPRI, was the world's second largest arms importer from 2010 to 2014. Saudi Arabia is considered a middle power. In addition to the GCC, it is an active member of the Organisation of Islamic Cooperation and OPEC. Following the unification of the Hejaz and Nejd kingdoms, the new state was named al-Mamlakah al-ʻArabīyah as-Suʻūdīyah by royal decree on 23 September 1932 by its founder, Abdulaziz Al Saud. Although this is translated as "the Kingdom of Saudi Arabia" in English, it means "the Saudi Arab kingdom", or "the Arab Saudi Kingdom"; the word "Saudi" is derived from the element as-Suʻūdīyah in the Arabic name of the country, a type of adjective known as a nisba, formed from the dynastic name of the Saudi royal family, the Al Saud. Its inclusion expresses the view. Al Saud is an Arabic name formed by adding the word Al, meaning "family of" or "House of", to the personal name of an ancestor.
In the case of the Al Saud, this is the father of the dynasty's 18th-century founder, Muhammad bin Saud. There is evidence that human habitation in the Arabian Peninsula dates back to about 125,000 years ago, it is now believed that the first modern humans to spread east across Asia left Africa about 75,000 years ago across the Bab-el-Mandeb connecting the Horn of Africa and Arabia. The Arabian peninsula is regarded as a central figure in our understanding of hominin evolution and dispersals. Arabia underwent an extreme environmental fluctuation in the Quaternary that led to profound evolutionary and demographic changes. Arabia has a rich Lower Paleolithic record, the quantity of Oldwan-like sites in the region indicate a significant role that Arabia had played in the early hominin colonization of Eurasia. In the Neolithic period, prominent cultures such as al-Magar whose epicenter lay in mod