Visible to Intel only — GUID: GUID-85936E3B-13FD-46F0-92EB-7E5F2AA98B3F
Visible to Intel only — GUID: GUID-85936E3B-13FD-46F0-92EB-7E5F2AA98B3F
p?lamch
Determines machine parameters for floating-point arithmetic.
Syntax
val = pslamch(ictxt, cmach)
val = pdlamch(ictxt, cmach)
Description
The p?lamchroutine determines single precision machine parameters.
Input Parameters
- ictxt
-
(global). INTEGER. The BLACS context handle in which the computation takes place.
- cmach
-
(global) CHARACTER*1.
Specifies the value to be returned by p?lamch:
= 'E' or 'e', p?lamch := eps
= 'S' or 's' , p?lamch := sfmin
= 'B' or 'b', p?lamch := base
= 'P' or 'p', p?lamch := eps*base
= 'N' or 'n', p?lamch := t
= 'R' or 'r', p?lamch := rnd
= 'M' or 'm', p?lamch := emin
= 'U' or 'u', p?lamch := rmin
= 'L' or 'l', p?lamch := emax
= 'O' or 'o', p?lamch := 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 - (baseemax)*(1-eps)
Output Parameters
- val
-
Value returned by the routine.