DTPTRS man page on IRIX

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DTPTRS(3F)							    DTPTRS(3F)

NAME
     DTPTRS - solve a triangular system of the form   A * X = B or A**T * X =
     B,

SYNOPSIS
     SUBROUTINE DTPTRS( UPLO, TRANS, DIAG, N, NRHS, AP, B, LDB, INFO )

	 CHARACTER	DIAG, TRANS, UPLO

	 INTEGER	INFO, LDB, N, NRHS

	 DOUBLE		PRECISION AP( * ), B( LDB, * )

PURPOSE
     DTPTRS solves a triangular system of the form

     where A is a triangular matrix of order N stored in packed format, and B
     is an N-by-NRHS matrix.  A check is made to verify that A is nonsingular.

ARGUMENTS
     UPLO    (input) CHARACTER*1
	     = 'U':  A is upper triangular;
	     = 'L':  A is lower triangular.

     TRANS   (input) CHARACTER*1
	     Specifies the form of the system of equations:
	     = 'N':  A * X = B	(No transpose)
	     = 'T':  A**T * X = B  (Transpose)
	     = 'C':  A**H * X = B  (Conjugate transpose = Transpose)

     DIAG    (input) CHARACTER*1
	     = 'N':  A is non-unit triangular;
	     = 'U':  A is unit triangular.

     N	     (input) INTEGER
	     The order of the matrix A.	 N >= 0.

     NRHS    (input) INTEGER
	     The number of right hand sides, i.e., the number of columns of
	     the matrix B.  NRHS >= 0.

     AP	     (input) DOUBLE PRECISION array, dimension (N*(N+1)/2)
	     The upper or lower triangular matrix A, packed columnwise in a
	     linear array.  The j-th column of A is stored in the array AP as
	     follows:  if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
	     if UPLO = 'L', AP(i + (j-1)*(2*n-j)/2) = A(i,j) for j<=i<=n.

     B	     (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
	     On entry, the right hand side matrix B.  On exit, if INFO = 0,
	     the solution matrix X.

									Page 1

DTPTRS(3F)							    DTPTRS(3F)

     LDB     (input) INTEGER
	     The leading dimension of the array B.  LDB >= max(1,N).

     INFO    (output) INTEGER
	     = 0:  successful exit
	     < 0:  if INFO = -i, the i-th argument had an illegal value
	     > 0:  if INFO = i, the i-th diagonal element of A is zero,
	     indicating that the matrix is singular and the solutions X have
	     not been computed.

									Page 2

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