/*Translated by FOR_C, v3.4.2 (-), on 07/09/115 at 08:31:19 */
/*FOR_C Options SET: ftn=u io=c no=p op=aimnv s=dbov str=l x=f - prototypes */
#include <math.h>
#include "fcrt.h"
#include "sgeslt.h"
#include <stdlib.h>
		/* PARAMETER translations */
#define	ZERO	0.e0
		/* end of PARAMETER translations */
 
void /*FUNCTION*/ sgeslt(
float *a,
long lda,
long n,
long ipvt[],
float b[])
{
#define A(I_,J_)	(*(a+(I_)*(lda)+(J_)))
	long int k, kb, l, nm1;
	float t;
		/* OFFSET Vectors w/subscript range: 1 to dimension */
	float *const B = &b[0] - 1;
	long *const Ipvt = &ipvt[0] - 1;
		/* end of OFFSET VECTORS */
 
	/* Copyright (c) 1996 California Institute of Technology, Pasadena, CA.
	 * ALL RIGHTS RESERVED.
	 * Based on Government Sponsored Research NAS7-03001.
	 *>> 1996-03-30 SGESLT Krogh  Added external statement.
	 *>> 1994-10-20 SGESLT Krogh  Changes to use M77CON
	 *>> 1987-08-18 SGESLT Lawson  Initial code.
	 *--S replaces "?": ?GESLT, ?DOT
	 *
	 *     This subroutine solves the system of equations  (A**t) * X = B
	 *     using the LU factorization of A given in the array A().
	 *     Here A**t denotes the transpose of A.
	 *     ------------------------------------------------------------------
	 *                        Subroutine arguments
	 *
	 *     A(,)  [in]  An array of size at least N x N.  On entry must
	 *            contain the LU factors of an N x N  matrix, A.  It is
	 *            expected that this factorization will have been computed by
	 *            use of _GEFA, either directly or indirectly via use of
	 *            _GEFS or _GEFSC.  This subr will not alter the contents of
	 *            A(,)
	 *
	 *     LDA  [in]  Leading dimensioning parameter for the array A(,).
	 *
	 *     N  [in]  The order of the original matrix, A.
	 *
	 *     IPVT()  [in]  An integer array of length at least N, containg a
	 *           record of the row interchanges made during factorization of
	 *           A.
	 *
	 *     B()  [inout]  On entry contains the right-side N-vector for the
	 *           problem, (A**t) * X = B.  On return contains the solution
	 *           N-vector, X.
	 *     ------------------------------------------------------------------
	 *     ERROR CONDITION
	 *
	 *        A DIVISION BY ZERO WILL OCCUR IF THE INPUT FACTOR CONTAINS A
	 *        ZERO ON THE DIAGONAL.  TECHNICALLY THIS INDICATES SINGULARITY
	 *        BUT IT IS OFTEN CAUSED BY IMPROPER ARGUMENTS OR IMPROPER
	 *        setting of LDA.  The user can avoid sending a singular matrix
	 *        to this subr by testing INFO (set by _GEFS or _GEFA) or
	 *        RCOND (set by _GEFSC or _GERC) before calling this subr.
	 *        Nonsingularity is indicated by INFO .eq. 0 or RCOND .ne. ZERO.
	 *     ------------------------------------------------------------------
	 *     LINPACK. THIS VERSION DATED 08/14/78 .
	 *     CLEVE MOLER, UNIVERSITY OF NEW MEXICO, ARGONNE NATIONAL LAB.
	 *     Ref: LINPACK Users' Guide, by J. J. Dongarra, C. B. Moler,
	 *     J. R. Bunch, and G. W. Stewart, publ by Soc. for Indust. and Appl.
	 *     Math, Philadelphia, 1979.
	 *     Adapted from LINPACK for the JPL Math77 library by
	 *     C. L. Lawson, JPL, Aug 1987.
	 *     ------------------------------------------------------------------
	 *     Subprograms referenced: SDOT
	 *     ------------------------------------------------------------------ */
	/*     ------------------------------------------------------------------ */
	nm1 = n - 1;
 
	/*        SOLVE  (A**t) * X = B
	 *        FIRST SOLVE  (U**t)*Y = B
	 * */
	for (k = 1; k <= n; k++)
	{
		t = sdot( k - 1, &A(k - 1,0), 1, &B[1], 1 );
		if (A(k - 1,k - 1) != ZERO)
		{
			B[k] = (B[k] - t)/A(k - 1,k - 1);
		}
		else
		{
			ermsg( "SGESLT", 1, 0, "A diagonal element is zero", '.' );
			return;
		}
	}
 
	/*        NOW SOLVE (L**t)*X = Y
	 * */
	for (kb = 1; kb <= nm1; kb++)
	{
		k = n - kb;
		B[k] += sdot( n - k, &A(k - 1,k), 1, &B[k + 1], 1 );
		l = Ipvt[k];
		if (l != k)
		{
			t = B[l];
			B[l] = B[k];
			B[k] = t;
		}
	}
	return;
#undef	A
} /* end of function */