REAL FUNCTION PSLAMCH( ICTXT, CMACH ) * * -- ScaLAPACK auxiliary routine (version 1.5) -- * University of Tennessee, Knoxville, Oak Ridge National Laboratory, * and University of California, Berkeley. * May 1, 1997 * * .. Scalar Arguments .. CHARACTER CMACH INTEGER ICTXT * .. * * Purpose * ======= * * PSLAMCH determines single precision machine parameters. * * Arguments * ========= * * ICTXT (global input) INTEGER * The BLACS context handle in which the computation takes * place. * * CMACH (global input) CHARACTER*1 * Specifies the value to be returned by PSLAMCH: * = 'E' or 'e', PSLAMCH := eps * = 'S' or 's , PSLAMCH := sfmin * = 'B' or 'b', PSLAMCH := base * = 'P' or 'p', PSLAMCH := eps*base * = 'N' or 'n', PSLAMCH := t * = 'R' or 'r', PSLAMCH := rnd * = 'M' or 'm', PSLAMCH := emin * = 'U' or 'u', PSLAMCH := rmin * = 'L' or 'l', PSLAMCH := emax * = 'O' or 'o', PSLAMCH := 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) * * ===================================================================== * * .. Local Scalars .. INTEGER IDUMM REAL TEMP * .. * .. External Subroutines .. EXTERNAL SGAMN2D, SGAMX2D * .. * .. External Functions .. LOGICAL LSAME REAL SLAMCH EXTERNAL LSAME, SLAMCH * .. * .. Executable Statements .. * TEMP = SLAMCH( CMACH ) * IF( LSAME( CMACH, 'E' ).OR.LSAME( CMACH, 'S' ).OR. $ LSAME( CMACH, 'M' ).OR.LSAME( CMACH, 'U' ) ) THEN CALL SGAMX2D( ICTXT, 'All', ' ', 1, 1, TEMP, 1, IDUMM, $ IDUMM, -1, -1, IDUMM ) ELSE IF( LSAME( CMACH, 'L' ).OR.LSAME( CMACH, 'O' ) ) THEN CALL SGAMN2D( ICTXT, 'All', ' ', 1, 1, TEMP, 1, IDUMM, $ IDUMM, -1, -1, IDUMM ) END IF * PSLAMCH = TEMP * * End of PSLAMCH * END