LAPACK  3.6.0
LAPACK: Linear Algebra PACKage
dlamchf77.f File Reference

Functions/Subroutines

double precision function dlamch (CMACH)
 DLAMCH More...
 
subroutine dlamc1 (BETA, T, RND, IEEE1)
 DLAMC1 More...
 
subroutine dlamc2 (BETA, T, RND, EPS, EMIN, RMIN, EMAX, RMAX)
 DLAMC2 More...
 
double precision function dlamc3 (A, B)
 DLAMC3 More...
 
subroutine dlamc4 (EMIN, START, BASE)
 DLAMC4 More...
 
subroutine dlamc5 (BETA, P, EMIN, IEEE, EMAX, RMAX)
 DLAMC5 More...
 

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.
Parameters
[in]A
[in]B
          The values A and B.
subroutine dlamc4 ( integer  EMIN,
double precision  START,
integer  BASE 
)

DLAMC4

Purpose:

 DLAMC4 is a service routine for DLAMC2.
Parameters
[out]EMIN
          The minimum exponent before (gradual) underflow, computed by
          setting A = START and dividing by BASE until the previous A
          can not be recovered.
[in]START
          The starting point for determining EMIN.
[in]BASE
          The base of the machine.
subroutine dlamc5 ( integer  BETA,
integer  P,
integer  EMIN,
logical  IEEE,
integer  EMAX,
double precision  RMAX 
)

DLAMC5

Purpose:

 DLAMC5 attempts to compute RMAX, the largest machine floating-point
 number, without overflow.  It assumes that EMAX + abs(EMIN) sum
 approximately to a power of 2.  It will fail on machines where this
 assumption does not hold, for example, the Cyber 205 (EMIN = -28625,
 EMAX = 28718).  It will also fail if the value supplied for EMIN is
 too large (i.e. too close to zero), probably with overflow.
Parameters
[in]BETA
          The base of floating-point arithmetic.
[in]P
          The number of base BETA digits in the mantissa of a
          floating-point value.
[in]EMIN
          The minimum exponent before (gradual) underflow.
[in]IEEE
          A logical flag specifying whether or not the arithmetic
          system is thought to comply with the IEEE standard.
[out]EMAX
          The largest exponent before overflow
[out]RMAX
          The largest machine floating-point number.