Developer Reference

  • 2020.2
  • 07/15/2020
  • Public Content
Contents

Common Parameters of the Trigonometric Transforms

This section provides description of array parameters that hold TT routine options:
ipar
,
dpar
and
spar
.
Initial values are assigned to the array parameters by the appropriate
?_init_trig_transform
and
?_commit_trig_transform
routines.
ipar
MKL_INT
array of size 128, holds integer data needed for Trigonometric Transform computations. Its elements are described in Table
"Elements of the ipar Array"
:
Elements of the ipar Array
Index
Description
0
Contains the size of the problem to solve. The
?_init_trig_transform
routine sets
ipar[0]
=
n
, and all subsequently called TT routines use
ipar[0]
as the size of the transform.
1
Contains error messaging options:
  • ipar[1]
    =-1 indicates that all error messages will be printed to the file
    MKL_Trig_Transforms_log.txt
    in the folder from which the routine is called. If the file does not exist, the routine tries to create it. If the attempt fails, the routine prints information that the file cannot be created to the standard output device.
  • ipar[1]
    =0 indicates that no error messages will be printed.
  • ipar[1]
    =1 (default) indicates that all error messages will be printed to the preconnected default output device (usually, screen).
In case of errors, each TT routine assigns a non-zero value to
stat
regardless of the
ipar[1]
setting.
2
Contains warning messaging options:
  • ipar[2]
    =-1 indicates that all warning messages will be printed to the file
    MKL_Trig_Transforms_log.txt
    in the directory from which the routine is called. If the file does not exist, the routine tries to create it. If the attempt fails, the routine prints information that the file cannot be created to the standard output device.
  • ipar[2]
    =0 indicates that no warning messages will be printed.
  • ipar[2]
    =1 (default) indicates that all warning messages will be printed to the preconnected default output device (usually, screen).
In case of warnings, the
stat
parameter will acquire a non-zero value regardless of the
ipar[2]
setting.
3 through 4
Reserved for future use.
5
Contains the type of the transform. The
?_init_trig_transform
routine sets
ipar[5]
=
tt_type
, and all subsequently called TT routines use
ipar[5]
as the type of the transform.
6
Contains the
stat
value returned by the last completed TT routine. Used to check that the previous call to a TT routine completed with
stat
=0.
7
Informs the
?_commit_trig_transform
routines whether to initialize data structures
dpar
(
spar
) and
handle
.
ipar[7]
=0 indicates that the routine should skip the initialization and only check correctness and consistency of the parameters. Otherwise, the routine initializes the data structures. The default value is 1.
The possibility to check correctness and consistency of input data without initializing data structures
dpar
,
spar
and
handle
enables avoiding performance losses in a repeated use of the same transform for different data vectors. Note that you can benefit from the opportunity that
ipar[7]
gives only if you are sure to have supplied proper tolerance value in the
dpar
or
spar
array. Otherwise, avoid tuning this parameter.
8
Contains message style options for TT routines.
If
ipar[8]
=0 then TT routines print all error and warning messages in Fortran-style notations.
The default value is 1.
When specifying message style options, be aware that by default, numbering of elements
in Fortran arrays
starts at 1
. The use of
ipar[8]
enables you to view messages in a more convenient style.
9
Specifies the number of OpenMP threads to run TT routines in the OpenMP environment of the
Intel® MKL
Poisson Solver. The default value is 1. You are highly recommended not to alter this value. See also Caveat on Parameter Modifications .
10
Specifies the mode of compatibility with FFTW. The default value is 0. Set the value to 1 to invoke compatibility with FFTW. In the latter case, results will not be normalized, because FFTW does not do this. It is highly recommended not to alter this value, but ra