Provided by: scalapack-doc_1.5-10_all
PDLAMCH - determine double precision machine parameters
DOUBLE PRECISION FUNCTION PDLAMCH( ICTXT, CMACH ) CHARACTER CMACH INTEGER ICTXT
PDLAMCH determines double precision machine parameters.
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)