?_init_Helmholtz_2D/?_init_Helmholtz

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 4/28/2026

Version

Public

?_init_Helmholtz_2D/?_init_Helmholtz_3D

Initializes basic data structures of the Fast 2D/3D Helmholtz Solver.

Syntax

void d_init_Helmholtz_2D(const double* ax, const double* bx, const double* ay,
                         const double* by, const MKL_INT* nx, const MKL_INT* ny,
                         const char* BCtype, const double* q, MKL_INT* ipar, double* dpar,
                         MKL_INT* stat);

void s_init_Helmholtz_2D(const float* ax, const float* bx, const float* ay, const float* by,
                         const MKL_INT* nx, const MKL_INT* ny, const char* BCtype,
                         const float* q, MKL_INT* ipar, float* spar, MKL_INT* stat);

void d_init_Helmholtz_3D(const double* ax, const double* bx, const double* ay,
                         const double* by, const double* az, const double* bz,
                         const MKL_INT* nx, const MKL_INT* ny, const MKL_INT* nz,
                         const char* BCtype, const double* q, MKL_INT* ipar, double* dpar,
                         MKL_INT* stat);

void s_init_Helmholtz_3D(const float* ax, const float* bx, const float* ay, const float* by,
                         const float* az, const float* bz, const MKL_INT* nx,
                         const MKL_INT* ny, const MKL_INT* nz, const char* BCtype,
                         const float* q, MKL_INT* ipar, float* spar, MKL_INT* stat);

Include Files

mkl.h

Input Parameters

Parameter Name	Description
`ax`	`double ` for `d_init_Helmholtz_2D/d_init_Helmholtz_3D`, `float` for `s_init_Helmholtz_2D/s_init_Helmholtz_3D`. The coordinate of the leftmost boundary of the domain along the x-axis.
`bx`	`double ` for `d_init_Helmholtz_2D/d_init_Helmholtz_3D`, `float` for `s_init_Helmholtz_2D/s_init_Helmholtz_3D`. The coordinate of the rightmost boundary of the domain along the x-axis.
`ay`	`double ` for `d_init_Helmholtz_2D/d_init_Helmholtz_3D`, `float` for `s_init_Helmholtz_2D/s_init_Helmholtz_3D`. The coordinate of the leftmost boundary of the domain along the y-axis.
`by`	`double ` for `d_init_Helmholtz_2D/d_init_Helmholtz_3D`, `float` for `s_init_Helmholtz_2D/s_init_Helmholtz_3D`. The coordinate of the rightmost boundary of the domain along the y-axis.
`az`	`double ` for `d_init_Helmholtz_3D`, `float` for `s_init_Helmholtz_3D`. The coordinate of the leftmost boundary of the domain along the z-axis. This parameter is needed only for the `?_init_Helmholtz_3D` routine.
`bz`	`double ` for `d_init_Helmholtz_3D`, `float` for `s_init_Helmholtz_3D`. The coordinate of the rightmost boundary of the domain along the z-axis. This parameter is needed only for the `?_init_Helmholtz_3D` routine.
`nx`	`MKL_INT *`. The number of mesh intervals along the x-axis.
`ny`	`MKL_INT *`. The number of mesh intervals along the y-axis.
`nz`	`MKL_INT *`. The number of mesh intervals along the z-axis. This parameter is needed only for the `?_init_Helmholtz_3D` routine.
`BCtype`	`char *`. Contains the type of boundary conditions on each boundary. Must contain four characters for `?_init_Helmholtz_2D` and six characters for `?_init_Helmholtz_3D`. Each of the characters can be ‘N’ (Neumann boundary condition), ‘D’ (Dirichlet boundary condition), or ‘P’ (periodic boundary conditions). Specify the types of boundary conditions for the boundaries in the following order: `\(bd_{a_x}\)`, `\(bd_{b_x}\)`, `\(bd_{a_y}\)`, `\(bd_{b_y}\)`, `\(bd_{a_z}\)`, and `\(bd_{b_z}\)`. Specify periodic boundary conditions on the respective boundaries in pairs (for example, ‘PPDD’ or ‘NNPP’ in the 2D case). The types of boundary conditions for the last two boundaries are needed only in the 3D case.
`q`	`double ` for `d_init_Helmholtz_2D/d_init_Helmholtz_3D`, `float` for `s_init_Helmholtz_2D/s_init_Helmholtz_3D`. The constant Helmholtz coefficient. Note that to solve Poisson or Laplace problem, you should set the value of `q` to 0.

Output Parameters

Parameter Name	Description
`ipar`	`MKL_INT` array of size 128. Contains integer data to be used by Fast Helmholtz Solver (for details, refer to ipar).
`dpar`	`double` array of size `\(\frac{5nx}{2}+7\)` in the 2D case or `\(\frac{5(nx+ny)}{2}+9\)` in the 3D case. Contains double-precision data to be used by Fast Helmholtz Solver (for details, refer to dpar).
`spar`	`float` array of size `\(\frac{5nx}{2}+7\)` in the 2D case or `\(\frac{5(nx+ny)}{2}+9\)` in the 3D case. Contains single-precision data to be used by Fast Helmholtz Solver (for details, refer to spar).
`stat`	`MKL_INT *`. Routine completion status, which is also written to `ipar[0]`. Continue to call other Poisson Solver routines only if the status is 0.

Description

The ?_init_Helmholtz_2D/?_init_Helmholtz_3D routines initialize basic data structures for Poisson Solver computations of the appropriate precision. All routines invoked after a call to a ?_init_Helmholtz_2D/?_init_Helmholtz_3D routine use values of the ipar, dpar and spar array parameters returned by the routine. Detailed description of the array parameters can be found in Common Parameters.

CAUTION:

Data structures initialized and created by 2D flavors of the routine cannot be used by 3D flavors of any Poisson Solver routines, and vice versa.

You can skip calls to these routines in your code. However, see Caveat on Parameter Modifications for information on initializing the data structures.

Return Values

Parameter Name	Value	Description
`stat`	`0`	The routine successfully completed the task. In general, to proceed with computations, the routine should complete with this `stat` value.
`stat`	`-99999`	The routine failed to complete the task because of a fatal error.

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