# dlamch.f - Man Page

INSTALL/dlamch.f

## Synopsis

### Functions/Subroutines

double precision function **dlamch** (cmach)**DLAMCH**

double precision function **dlamc3** (a, b)**DLAMC3**

## Function/Subroutine Documentation

### double precision function dlamc3 (double precision a, double precision b)

**DLAMC3 Purpose:**

DLAMC3 is intended to force A and B to be stored prior to doing the addition of A and B , for use in situations where optimizers might hold one of these in a register.

**Author**LAPACK is a software package provided by Univ. of Tennessee, Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..

**Parameters***A*A is a DOUBLE PRECISION

*B*B is a DOUBLE PRECISION The values A and B.

Definition at line **171** of file **dlamch.f**.

### double precision function dlamch (character cmach)

**DLAMCH**

**Purpose:**

DLAMCH determines double precision machine parameters.

**Parameters***CMACH*CMACH is CHARACTER*1 Specifies the value to be returned by DLAMCH: = 'E' or 'e', DLAMCH := eps = 'S' or 's , DLAMCH := sfmin = 'B' or 'b', DLAMCH := base = 'P' or 'p', DLAMCH := eps*base = 'N' or 'n', DLAMCH := t = 'R' or 'r', DLAMCH := rnd = 'M' or 'm', DLAMCH := emin = 'U' or 'u', DLAMCH := rmin = 'L' or 'l', DLAMCH := emax = 'O' or 'o', DLAMCH := 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)

**Author**Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **68** of file **dlamch.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man pages dlamc3(3) and dlamch(3) are aliases of dlamch.f(3).

Tue Nov 28 2023 12:08:41 Version 3.12.0 LAPACK