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DOUBLE PRECISION FUNCTION PDLAMCH( ICTXT, CMACH )
*
* -- ScaLAPACK auxiliary routine (version 1.7) --
* University of Tennessee, Knoxville, Oak Ridge National Laboratory,
* and University of California, Berkeley.
* May 1, 1997
*
* .. Scalar Arguments ..
CHARACTER CMACH
INTEGER ICTXT
* ..
*
* Purpose
* =======
*
* PDLAMCH determines double 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 PDLAMCH:
* = 'E' or 'e', PDLAMCH := eps
* = 'S' or 's , PDLAMCH := sfmin
* = 'B' or 'b', PDLAMCH := base
* = 'P' or 'p', PDLAMCH := eps*base
* = 'N' or 'n', PDLAMCH := t
* = 'R' or 'r', PDLAMCH := rnd
* = 'M' or 'm', PDLAMCH := emin
* = 'U' or 'u', PDLAMCH := rmin
* = 'L' or 'l', PDLAMCH := emax
* = 'O' or 'o', PDLAMCH := 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
DOUBLE PRECISION TEMP
* ..
* .. External Subroutines ..
EXTERNAL DGAMN2D, DGAMX2D
* ..
* .. External Functions ..
LOGICAL LSAME
DOUBLE PRECISION DLAMCH
EXTERNAL DLAMCH, LSAME
* ..
* .. Executable Statements ..
*
TEMP = DLAMCH( CMACH )
*
IF( LSAME( CMACH, 'E' ).OR.LSAME( CMACH, 'S' ).OR.
$ LSAME( CMACH, 'M' ).OR.LSAME( CMACH, 'U' ) ) THEN
CALL DGAMX2D( ICTXT, 'All', ' ', 1, 1, TEMP, 1, IDUMM,
$ IDUMM, -1, -1, IDUMM )
ELSE IF( LSAME( CMACH, 'L' ).OR.LSAME( CMACH, 'O' ) ) THEN
CALL DGAMN2D( ICTXT, 'All', ' ', 1, 1, TEMP, 1, IDUMM,
$ IDUMM, -1, -1, IDUMM )
END IF
*
PDLAMCH = TEMP
*
* End of PDLAMCH
*
END
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