---
name: "pslamch"
section: "3"
platform: "linux"
package: "scalapack-doc"
version: "1.5-11"
release: "Debian 11 (Bullseye)"
platforms: ["linux"]
url: "https://new.carta.tech/pslamch"
---

# pslamch(3)

determine single precision machine parameters

## NAME

PSLAMCH - determine single precision machine parameters

## SYNOPSIS

- REAL FUNCTION

  PSLAMCH( ICTXT, CMACH )

- 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)