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diff --git a/math/slalib/doc/smat.hlp b/math/slalib/doc/smat.hlp new file mode 100644 index 00000000..ad2b1f2d --- /dev/null +++ b/math/slalib/doc/smat.hlp @@ -0,0 +1,60 @@ +.help smat Jun99 "Slalib Package" +.nf + + SUBROUTINE slSMAT (N, A, Y, D, JF, IW) + + - - - - - + S M A T + - - - - - + + Matrix inversion & solution of simultaneous equations + (single precision) + + For the set of n simultaneous equations in n unknowns: + A.Y = X + + where: + A is a non-singular N x N matrix + Y is the vector of N unknowns + X is the known vector + + SMATRX computes: + the inverse of matrix A + the determinant of matrix A + the vector of N unknowns + + Arguments: + + symbol type dimension before after + + N int no. of unknowns unchanged + A real (N,N) matrix inverse + Y real (N) vector solution + D real - determinant + * JF int - singularity flag + IW int (N) - workspace + + * JF is the singularity flag. If the matrix is non-singular, + JF=0 is returned. If the matrix is singular, JF=-1 & D=0.0 are + returned. In the latter case, the contents of array A on return + are undefined. + + Algorithm: + Gaussian elimination with partial pivoting. + + Speed: + Very fast. + + Accuracy: + Fairly accurate - errors 1 to 4 times those of routines optimized + for accuracy. + + Note: replaces the obsolete slSMATRX routine. + + P.T.Wallace Starlink 10 September 1990 + + Copyright (C) 1995 Rutherford Appleton Laboratory + Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. + +.fi +.endhelp |