#include "clapack.h"

integer ieeeck_(integer *ispec, real *zero, real *one)
{
    /* System generated locals */
    integer ret_val;

    /* Local variables */
    real nan1, nan2, nan3, nan4, nan5, nan6, neginf, posinf, negzro, newzro;


/*  -- LAPACK auxiliary routine (version 3.1) -- */
/*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/*     November 2006 */

/*     .. Scalar Arguments .. */
/*     .. */

/*  Purpose */
/*  ======= */

/*  IEEECK is called from the ILAENV to verify that Infinity and */
/*  possibly NaN arithmetic is safe (i.e. will not trap). */

/*  Arguments */
/*  ========= */

/*  ISPEC   (input) INTEGER */
/*          Specifies whether to test just for inifinity arithmetic */
/*          or whether to test for infinity and NaN arithmetic. */
/*          = 0: Verify infinity arithmetic only. */
/*          = 1: Verify infinity and NaN arithmetic. */

/*  ZERO    (input) REAL */
/*          Must contain the value 0.0 */
/*          This is passed to prevent the compiler from optimizing */
/*          away this code. */

/*  ONE     (input) REAL */
/*          Must contain the value 1.0 */
/*          This is passed to prevent the compiler from optimizing */
/*          away this code. */

/*  RETURN VALUE:  INTEGER */
/*          = 0:  Arithmetic failed to produce the correct answers */
/*          = 1:  Arithmetic produced the correct answers */

/*     .. Local Scalars .. */
/*     .. */
/*     .. Executable Statements .. */
    ret_val = 1;

    posinf = *one / *zero;
    if (posinf <= *one) {
	ret_val = 0;
	return ret_val;
    }

    neginf = -(*one) / *zero;
    if (neginf >= *zero) {
	ret_val = 0;
	return ret_val;
    }

    negzro = *one / (neginf + *one);
    if (negzro != *zero) {
	ret_val = 0;
	return ret_val;
    }

    neginf = *one / negzro;
    if (neginf >= *zero) {
	ret_val = 0;
	return ret_val;
    }

    newzro = negzro + *zero;
    if (newzro != *zero) {
	ret_val = 0;
	return ret_val;
    }

    posinf = *one / newzro;
    if (posinf <= *one) {
	ret_val = 0;
	return ret_val;
    }

    neginf *= posinf;
    if (neginf >= *zero) {
	ret_val = 0;
	return ret_val;
    }

    posinf *= posinf;
    if (posinf <= *one) {
	ret_val = 0;
	return ret_val;
    }




/*     Return if we were only asked to check infinity arithmetic */

    if (*ispec == 0) {
	return ret_val;
    }

    nan1 = posinf + neginf;

    nan2 = posinf / neginf;

    nan3 = posinf / posinf;

    nan4 = posinf * *zero;

    nan5 = neginf * negzro;

    nan6 = nan5 * 0.f;

    if (nan1 == nan1) {
	ret_val = 0;
	return ret_val;
    }

    if (nan2 == nan2) {
	ret_val = 0;
	return ret_val;
    }

    if (nan3 == nan3) {
	ret_val = 0;
	return ret_val;
    }

    if (nan4 == nan4) {
	ret_val = 0;
	return ret_val;
    }

    if (nan5 == nan5) {
	ret_val = 0;
	return ret_val;
    }

    if (nan6 == nan6) {
	ret_val = 0;
	return ret_val;
    }

    return ret_val;
} /* ieeeck_ */
