1DLAMCH  ‐  double  precision  machine parameters DOUBLE PRECISION
2FUNCTION DLAMCH( CMACH )
3    CHARACTER CMACH DLAMCH determines  double  precision  machine
4parameters.
5
6CMACH   (input) CHARACTER*1 Specifies the value to be returned by
7DLAMCH:
8= 'E' or 'e',   DLAMCH := eps
9= 'S' or 's ,   DLAMCH := sfmin
10= 'B' or 'b',   DLAMCH := base
11= 'P' or 'p',   DLAMCH := eps*base
12= 'N' or 'n',   DLAMCH := t
13= 'R' or 'r',   DLAMCH := rnd
14= 'M' or 'm',   DLAMCH := emin
15= 'U' or 'u',   DLAMCH := rmin
16= 'L' or 'l',   DLAMCH := emax
17= 'O' or 'o',   DLAMCH := rmax
18
19where eps   = relative machine precision sfmin  =  safe  minimum,
20such  that  1/sfmin does not overflow base  = base of the machine
21prec  = eps*base t     = number of (base) digits in the  mantissa
22rnd    = 1.0 when rounding occurs in addition, 0.0 otherwise emin
23= minimum exponent before (gradual) underflow rmin   =  underflow
24threshold  ‐ base**(emin‐1) emax  = largest exponent before over‐
25flow rmax  = overflow threshold  ‐ (base**emax)*(1‐eps)
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