slamc4.c

来自「NIST Handwriting OCR Testbed」· C语言 代码 · 共 98 行

/*
* ======================================================================
* NIST Guide to Available Math Software.
* Fullsource for module SSYEVX.C from package CLAPACK.
* Retrieved from NETLIB on Fri Mar 10 14:23:44 2000.
* ======================================================================
*/
#include <f2c.h>

/* Subroutine */ int slamc4_(integer *emin, real *start, integer *base)
{
/*  -- LAPACK auxiliary routine (version 2.0) --   
       Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   
       Courant Institute, Argonne National Lab, and Rice University   
       October 31, 1992   


    Purpose   
    =======   

    SLAMC4 is a service routine for SLAMC2.   

    Arguments   
    =========   

    EMIN    (output) EMIN   
            The minimum exponent before (gradual) underflow, computed by 
  
            setting A = START and dividing by BASE until the previous A   
            can not be recovered.   

    START   (input) REAL   
            The starting point for determining EMIN.   

    BASE    (input) INTEGER   
            The base of the machine.   

   ===================================================================== 
*/
    /* System generated locals */
    integer i__1;
    real r__1;
    /* Local variables */
    static real zero, a;
    static integer i;
    static real rbase, b1, b2, c1, c2, d1, d2;
    extern doublereal slamc3_(real *, real *);
    static real one;



    a = *start;
    one = 1.f;
    rbase = one / *base;
    zero = 0.f;
    *emin = 1;
    r__1 = a * rbase;
    b1 = slamc3_(&r__1, &zero);
    c1 = a;
    c2 = a;
    d1 = a;
    d2 = a;
/* +    WHILE( ( C1.EQ.A ).AND.( C2.EQ.A ).AND.   
      $       ( D1.EQ.A ).AND.( D2.EQ.A )      )LOOP */
L10:
    if (c1 == a && c2 == a && d1 == a && d2 == a) {
	--(*emin);
	a = b1;
	r__1 = a / *base;
	b1 = slamc3_(&r__1, &zero);
	r__1 = b1 * *base;
	c1 = slamc3_(&r__1, &zero);
	d1 = zero;
	i__1 = *base;
	for (i = 1; i <= *base; ++i) {
	    d1 += b1;
/* L20: */
	}
	r__1 = a * rbase;
	b2 = slamc3_(&r__1, &zero);
	r__1 = b2 / rbase;
	c2 = slamc3_(&r__1, &zero);
	d2 = zero;
	i__1 = *base;
	for (i = 1; i <= *base; ++i) {
	    d2 += b2;
/* L30: */
	}
	goto L10;
    }
/* +    END WHILE */

    return 0;

/*     End of SLAMC4 */

} /* slamc4_ */