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.TH DLAMCH l "15 June 2000" "LAPACK version 3.0" ")"
.SH NAME
DLAMCH - determine double precision machine parameters
.SH SYNOPSIS
.TP 17
DOUBLE PRECISION
FUNCTION DLAMCH( CMACH )
.TP 17
.ti +4
CHARACTER
CMACH
.SH PURPOSE
DLAMCH determines double precision machine parameters.
.SH ARGUMENTS
.TP 8
CMACH (input) CHARACTER*1
Specifies the value to be returned by DLAMCH:
.br
= 'E' or 'e', DLAMCH := eps
.br
= 'S' or 's , DLAMCH := sfmin
.br
= 'B' or 'b', DLAMCH := base
.br
= 'P' or 'p', DLAMCH := eps*base
.br
= 'N' or 'n', DLAMCH := t
.br
= 'R' or 'r', DLAMCH := rnd
.br
= 'M' or 'm', DLAMCH := emin
.br
= 'U' or 'u', DLAMCH := rmin
.br
= 'L' or 'l', DLAMCH := emax
.br
= 'O' or 'o', DLAMCH := rmax
where
.TP 6
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)
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