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REAL FUNCTION SLAMCH( CMACH )
* * -- LAPACK auxiliary routine (version 3.3.0) -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * Based on LAPACK DLAMCH but with Fortran 95 query functions * See: http://www.cs.utk.edu/~luszczek/lapack/lamch.html * and http://www.netlib.org/lapack-dev/lapack-coding/program-style.html#id2537289 * July 2010 * * .. Scalar Arguments .. CHARACTER CMACH * .. * * Purpose * ======= * * SLAMCH determines single precision machine parameters. * * Arguments * ========= * * CMACH (input) CHARACTER*1 * Specifies the value to be returned by SLAMCH: * = 'E' or 'e', SLAMCH := eps * = 'S' or 's , SLAMCH := sfmin * = 'B' or 'b', SLAMCH := base * = 'P' or 'p', SLAMCH := eps*base * = 'N' or 'n', SLAMCH := t * = 'R' or 'r', SLAMCH := rnd * = 'M' or 'm', SLAMCH := emin * = 'U' or 'u', SLAMCH := rmin * = 'L' or 'l', SLAMCH := emax * = 'O' or 'o', SLAMCH := rmax * * where * * eps = relative machine precision * sfmin = safe minimum, such that 1/sfmin does not overflow * base = base of the machine * prec = eps*base * t = number of (base) digits in the mantissa * rnd = 1.0 when rounding occurs in addition, 0.0 otherwise * emin = minimum exponent before (gradual) underflow * rmin = underflow threshold - base**(emin-1) * emax = largest exponent before overflow * rmax = overflow threshold - (base**emax)*(1-eps) * * ===================================================================== * * .. Parameters .. REAL ONE, ZERO PARAMETER ( ONE = 1.0E+0, ZERO = 0.0E+0 ) * .. * .. Local Scalars .. REAL RND, EPS, SFMIN, SMALL, RMACH * .. * .. External Functions .. LOGICAL LSAME EXTERNAL LSAME * .. * .. Intrinsic Functions .. INTRINSIC DIGITS, EPSILON, HUGE, MAXEXPONENT, $ MINEXPONENT, RADIX, TINY * .. * .. Executable Statements .. * * * Assume rounding, not chopping. Always. * RND = ONE * IF( ONE.EQ.RND ) THEN EPS = EPSILON(ZERO) * 0.5 ELSE EPS = EPSILON(ZERO) END IF * IF( LSAME( CMACH, 'E' ) ) THEN RMACH = EPS ELSE IF( LSAME( CMACH, 'S' ) ) THEN SFMIN = TINY(ZERO) SMALL = ONE / HUGE(ZERO) IF( SMALL.GE.SFMIN ) THEN * * Use SMALL plus a bit, to avoid the possibility of rounding * causing overflow when computing 1/sfmin. * SFMIN = SMALL*( ONE+EPS ) END IF RMACH = SFMIN ELSE IF( LSAME( CMACH, 'B' ) ) THEN RMACH = RADIX(ZERO) ELSE IF( LSAME( CMACH, 'P' ) ) THEN RMACH = EPS * RADIX(ZERO) ELSE IF( LSAME( CMACH, 'N' ) ) THEN RMACH = DIGITS(ZERO) ELSE IF( LSAME( CMACH, 'R' ) ) THEN RMACH = RND ELSE IF( LSAME( CMACH, 'M' ) ) THEN RMACH = MINEXPONENT(ZERO) ELSE IF( LSAME( CMACH, 'U' ) ) THEN RMACH = tiny(zero) ELSE IF( LSAME( CMACH, 'L' ) ) THEN RMACH = MAXEXPONENT(ZERO) ELSE IF( LSAME( CMACH, 'O' ) ) THEN RMACH = HUGE(ZERO) ELSE RMACH = ZERO END IF * SLAMCH = RMACH RETURN * * End of SLAMCH * END ************************************************************************ * REAL FUNCTION SLAMC3( A, B ) * * -- LAPACK auxiliary routine (version 3.3.0) -- * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. * November 2010 * * .. Scalar Arguments .. REAL A, B * .. * * Purpose * ======= * * SLAMC3 is intended to force A and B to be stored prior to doing * the addition of A and B , for use in situations where optimizers * might hold one of these in a register. * * Arguments * ========= * * A (input) REAL * B (input) REAL * The values A and B. * * ===================================================================== * * .. Executable Statements .. * SLAMC3 = A + B * RETURN * * End of SLAMC3 * END * ************************************************************************ |