▁a ▁district ▁of ▁J ä mt land ▁in ▁Sweden . ▁The ▁provinces ▁in ▁Nor r land ▁were ▁never ▁divided ▁into ▁hundreds ▁and ▁instead ▁the ▁court ▁district ▁( t ings lag ) ▁served ▁as ▁the ▁basic ▁division ▁of ▁rural ▁areas . ▁ ▁References ▁▁ ▁Category : Pop ulated ▁places ▁in ▁Berg ▁Municip ality ▁Category : J ä mt land <0x0A> </s> ▁A ▁computer ▁algebra ▁system ▁( C AS ) ▁is ▁any ▁mathematical ▁software ▁with ▁the ▁ability ▁to ▁manipulate ▁mathematical ▁expressions ▁in ▁a ▁way ▁similar ▁to ▁the ▁traditional ▁manual ▁comput ations ▁of ▁mathemat icians ▁and ▁scient ists . ▁The ▁development ▁of ▁the ▁computer ▁algebra ▁systems ▁in ▁the ▁second ▁half ▁of ▁the ▁ 2 0 th ▁century ▁is ▁part ▁of ▁the ▁discipline ▁of ▁" comput er ▁algebra " ▁or ▁" symbol ic ▁computation ", ▁which ▁has ▁sp ur red ▁work ▁in ▁algorithms ▁over ▁mathematical ▁objects ▁such ▁as ▁polynomials . ▁ ▁Computer ▁algebra ▁systems ▁may ▁be ▁divided ▁into ▁two ▁classes : ▁special ized ▁and ▁general - pur pose . ▁The ▁special ized ▁ones ▁are ▁devoted ▁to ▁a ▁specific ▁part ▁of ▁mathematics , ▁such ▁as ▁number ▁theory , ▁group ▁theory , ▁or ▁teaching ▁of ▁elementary ▁mathematics . ▁ ▁General - pur pose ▁computer ▁algebra ▁systems ▁aim ▁to ▁be ▁useful ▁to ▁a ▁user ▁working ▁in ▁any ▁scientific ▁field ▁that ▁requires ▁manip ulation ▁of ▁mathematical ▁expressions . ▁To ▁be ▁useful , ▁a ▁general - pur pose ▁computer ▁algebra ▁system ▁must ▁include ▁various ▁features ▁such ▁as : ▁a ▁user ▁interface ▁allowing ▁a ▁user ▁to ▁enter ▁and ▁display ▁mathematical ▁formulas , ▁typically