Developer Reference

  • 0.9
  • 09/09/2020
  • Public Content
Contents

p?lamch

Determines machine parameters for floating-point arithmetic.

Syntax

float
pslamch
(
MKL_INT
*ictxt
,
char
*cmach
);
double
pdlamch
(
MKL_INT
*ictxt
,
char
*cmach
);
Include Files
  • mkl_scalapack.h
Description
The
p?lamch
function
determines single precision machine parameters.
Input Parameters
ictxt
(global). The BLACS context handle in which the computation takes place.
cmach
(global)
Specifies the value to be returned by
p?lamch
:
=
'E'
or
'e'
,
p?lamch
:=
eps
=
'S'
or
's'
,
p?lamch
:=
sfmin
=
'B'
or
'b'
,
p?lamch
:=
base
=
'P'
or
'p'
,
p?lamch
:=
eps*base
=
'N'
or
'n'
,
p?lamch
:=
t
=
'R'
or
'r'
,
p?lamch
:=
rnd
=
'M'
or
'm'
,
p?lamch
:=
emin
=
'U'
or
'u'
,
p?lamch
:=
rmin
=
'L'
or
'l'
,
p?lamch
:=
emax
=
'O'
or
'o'
,
p?lamch
:=
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
)
Output Parameters
val
Value returned by the
function
.

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804