slamch (l) - Linux Manuals

slamch: single precision machine parameters

NAME

SLAMCH - single precision machine parameters

SYNOPSIS

REAL FUNCTION
SLAMCH( CMACH )

    
CHARACTER CMACH

PURPOSE

SLAMCH determines single precision machine parameters.

ARGUMENTS

CMACH (input) CHARACTER*1
Specifies the value to be returned by SLAMCH:
= aqEaq or aqeaq, SLAMCH := eps
= aqSaq or aqs , SLAMCH := sfmin
= aqBaq or aqbaq, SLAMCH := base
= aqPaq or aqpaq, SLAMCH := eps*base
= aqNaq or aqnaq, SLAMCH := t
= aqRaq or aqraq, SLAMCH := rnd
= aqMaq or aqmaq, SLAMCH := emin
= aqUaq or aquaq, SLAMCH := rmin
= aqLaq or aqlaq, SLAMCH := emax
= aqOaq or aqoaq, SLAMCH := 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)

Pages related to slamch

  • slamch (3)
  • slamchtst (l)
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  • sla_gbamv (l) - performs one of the matrix-vector operations y := alpha*abs(A)*abs(x) + beta*abs(y),
  • sla_gbrcond (l) - SLA_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 infinity-norm condition number
  • sla_gbrfsx_extended (l) - computes ..
  • sla_geamv (l) - performs one of the matrix-vector operations y := alpha*abs(A)*abs(x) + beta*abs(y),
  • sla_gercond (l) - SLA_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 infinity-norm condition number