/* elmhes.f -- translated by f2c (version 19961017).
   You must link the resulting object file with the libraries:
	-lf2c -lm   (in that order)
*/

#include "f2c.h"

/* Subroutine */ int elmhes_(integer *nm, integer *n, integer *low, integer *
	igh, doublereal *a, integer *int__)
{
    /* System generated locals */
    integer a_dim1, a_offset, i__1, i__2, i__3;
    doublereal d__1;

    /* Local variables */
    static integer i__, j, m;
    static doublereal x, y;
    static integer la, mm1, kp1, mp1;



/*     THIS SUBROUTINE IS A TRANSLATION OF THE ALGOL PROCEDURE ELMHES, */
/*     NUM. MATH. 12, 349-368(1968) BY MARTIN AND WILKINSON. */
/*     HANDBOOK FOR AUTO. COMP., VOL.II-LINEAR ALGEBRA, 339-358(1971). */

/*     GIVEN A REAL GENERAL MATRIX, THIS SUBROUTINE */
/*     REDUCES A SUBMATRIX SITUATED IN ROWS AND COLUMNS */
/*     LOW THROUGH IGH TO UPPER HESSENBERG FORM BY */
/*     STABILIZED ELEMENTARY SIMILARITY TRANSFORMATIONS. */

/*     ON INPUT */

/*        NM MUST BE SET TO THE ROW DIMENSION OF TWO-DIMENSIONAL */
/*          ARRAY PARAMETERS AS DECLARED IN THE CALLING PROGRAM */
/*          DIMENSION STATEMENT. */

/*        N IS THE ORDER OF THE MATRIX. */

/*        LOW AND IGH ARE INTEGERS DETERMINED BY THE BALANCING */
/*          SUBROUTINE  BALANC.  IF  BALANC  HAS NOT BEEN USED, */
/*          SET LOW=1, IGH=N. */

/*        A CONTAINS THE INPUT MATRIX. */

/*     ON OUTPUT */

/*        A CONTAINS THE HESSENBERG MATRIX.  THE MULTIPLIERS */
/*          WHICH WERE USED IN THE REDUCTION ARE STORED IN THE */
/*          REMAINING TRIANGLE UNDER THE HESSENBERG MATRIX. */

/*        INT CONTAINS INFORMATION ON THE ROWS AND COLUMNS */
/*          INTERCHANGED IN THE REDUCTION. */
/*          ONLY ELEMENTS LOW THROUGH IGH ARE USED. */

/*     QUESTIONS AND COMMENTS SHOULD BE DIRECTED TO BURTON S. GARBOW, */
/*     MATHEMATICS AND COMPUTER SCIENCE DIV, ARGONNE NATIONAL LABORATORY 
*/

/*     THIS VERSION DATED AUGUST 1983. */

/*     ------------------------------------------------------------------ 
*/

    /* Parameter adjustments */
    a_dim1 = *nm;
    a_offset = a_dim1 + 1;
    a -= a_offset;
    --int__;

    /* Function Body */
    la = *igh - 1;
    kp1 = *low + 1;
    if (la < kp1) {
	goto L200;
    }

    i__1 = la;
    for (m = kp1; m <= i__1; ++m) {
	mm1 = m - 1;
	x = 0.;
	i__ = m;

	i__2 = *igh;
	for (j = m; j <= i__2; ++j) {
	    if ((d__1 = a[j + mm1 * a_dim1], abs(d__1)) <= abs(x)) {
		goto L100;
	    }
	    x = a[j + mm1 * a_dim1];
	    i__ = j;
L100:
	    ;
	}

	int__[m] = i__;
	if (i__ == m) {
	    goto L130;
	}
/*     .......... INTERCHANGE ROWS AND COLUMNS OF A .......... */
	i__2 = *n;
	for (j = mm1; j <= i__2; ++j) {
	    y = a[i__ + j * a_dim1];
	    a[i__ + j * a_dim1] = a[m + j * a_dim1];
	    a[m + j * a_dim1] = y;
/* L110: */
	}

	i__2 = *igh;
	for (j = 1; j <= i__2; ++j) {
	    y = a[j + i__ * a_dim1];
	    a[j + i__ * a_dim1] = a[j + m * a_dim1];
	    a[j + m * a_dim1] = y;
/* L120: */
	}
/*     .......... END INTERCHANGE .......... */
L130:
	if (x == 0.) {
	    goto L180;
	}
	mp1 = m + 1;

	i__2 = *igh;
	for (i__ = mp1; i__ <= i__2; ++i__) {
	    y = a[i__ + mm1 * a_dim1];
	    if (y == 0.) {
		goto L160;
	    }
	    y /= x;
	    a[i__ + mm1 * a_dim1] = y;

	    i__3 = *n;
	    for (j = m; j <= i__3; ++j) {
/* L140: */
		a[i__ + j * a_dim1] -= y * a[m + j * a_dim1];
	    }

	    i__3 = *igh;
	    for (j = 1; j <= i__3; ++j) {
/* L150: */
		a[j + m * a_dim1] += y * a[j + i__ * a_dim1];
	    }

L160:
	    ;
	}

L180:
	;
    }

L200:
    return 0;
} /* elmhes_ */