dlamch (l)  Linux Man Pages
dlamch: double precision machine parameters
Command to display dlamch
manual in Linux: $ man l dlamch
NAME
DLAMCH  double precision machine parameters
SYNOPSIS
 DOUBLE PRECISION

FUNCTION DLAMCH( CMACH )

CHARACTER
CMACH
PURPOSE
DLAMCH determines double precision machine parameters.
ARGUMENTS
 CMACH (input) CHARACTER*1

Specifies the value to be returned by DLAMCH:
= aqEaq or aqeaq, DLAMCH := eps
= aqSaq or aqs , DLAMCH := sfmin
= aqBaq or aqbaq, DLAMCH := base
= aqPaq or aqpaq, DLAMCH := eps*base
= aqNaq or aqnaq, DLAMCH := t
= aqRaq or aqraq, DLAMCH := rnd
= aqMaq or aqmaq, DLAMCH := emin
= aqUaq or aquaq, DLAMCH := rmin
= aqLaq or aqlaq, DLAMCH := emax
= aqOaq or aqoaq, 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**(emin1)
emax = largest exponent before overflow
rmax = overflow threshold  (base**emax)*(1eps)
Pages related to dlamch
 dlamch (3)
 dlamchtst (l)
 dlamrg (l)  will create a permutation list which will merge the elements of A (which is composed of two independently sorted sets) into a single set which is sorted in ascending order
 dla_gbamv (l)  performs one of the matrixvector operations y := alpha*abs(A)*abs(x) + beta*abs(y),
 dla_gbrcond (l)  DLA_GERCOND Estimate the Skeel condition number of op(A) * op2(C) where op2 is determined by CMODE as follows CMODE = 1 op2(C) = C CMODE = 0 op2(C) = I CMODE = 1 op2(C) = inv(C) The Skeel condition number cond(A) = norminf( inv(A)A ) is computed by computing scaling factors R such that diag(R)*A*op2(C) is row equilibrated and computing the standard infinitynorm condition number
 dla_gbrfsx_extended (l)  computes ..
 dla_geamv (l)  performs one of the matrixvector operations y := alpha*abs(A)*abs(x) + beta*abs(y),
 dla_gercond (l)  DLA_GERCOND estimate the Skeel condition number of op(A) * op2(C) where op2 is determined by CMODE as follows CMODE = 1 op2(C) = C CMODE = 0 op2(C) = I CMODE = 1 op2(C) = inv(C) The Skeel condition number cond(A) = norminf( inv(A)A ) is computed by computing scaling factors R such that diag(R)*A*op2(C) is row equilibrated and computing the standard infinitynorm condition number