kml_fft(f)_plan_dft_c2r
建立单个连续数据序列n维C2R变换的plan。
接口定义
C interface:
kml_fft_plan kml_fft_plan_dft_c2r(int rank, const int *n, kml_fft_complex *in, double *out, unsigned flags);
kml_fftf_plan kml_fftf_plan_dft_c2r(int rank, const int *n, kml_fftf_complex *in, float *out, unsigned flags);
Fortran interface:
RES = KML_FFT_PLAN_DFT_C2R(RANK, N, IN, OUT, FLAGS);
RES = KML_FFTF_PLAN_DFT_C2R(RANK, N, IN, OUT, FLAGS);
返回值
函数返回一个kml_fft(f)_plan类型的结构体指针。将该对象作为参数传入kml_fft(f)_execute函数中使用，将对当前提供的输入in和输出out执行FFT变换；另外，也可以通过将该对象作为参数传入kml_fft(f)_execute_dft_c2r函数中以对新的输入in和输出out执行FFT变换。
如果函数返回非空指针，则表示plan执行成功，否则表示执行失败。
参数
参数名 |
数据类型 |
描述 |
输入/输出 |
|---|---|---|---|
rank |
int |
FFT变换的维度是rank，约束：1 <= rank <= 3。 |
输入 |
n |
const int* |
n是维度为rank的数组，包含FFT序列每一维度的大小，约束：n[i] >= 1, for i in 0 to rank - 1。 |
输入 |
in |
|
输入待变换的数据。 |
输入 |
out |
|
输出快速傅里叶变换后的数据。 |
输出 |
flags |
unsigned int |
planning选项，未使用。 |
输入 |
依赖
C: "kfft.h"
Fortran: "kfft.f03"
示例
C interface:
int rank = 2;
int *n;
n = (int*)kml_fft_malloc(sizeof(int) * rank);
n[0] = 2;
n[1] = 4;
double init[6][2] = {{120, 0}, {8, 8}, {0, 0}, {0, 16}, {0, 16}, {-8, 8}};
kml_fft_complex *in;
in = (kml_fft_complex*)kml_fft_malloc(sizeof(kml_fft_complex) * n[0] * (n[1] / 2 + 1));
for (int i = 0; i < n[0] * (n[1] / 2 + 1); i++) {
in[i].r = init[i][0];
in[i].i = init[i][1];
}
double *out;
out = (double*)kml_fft_malloc(sizeof(double) * n[0] * n[1]);
kml_fft_plan plan;
plan = kml_fft_plan_dft_c2r(rank, n, in, out, KML_FFT_ESTIMATE);
kml_fft_execute_dft_c2r(plan, in, out);
kml_fft_destroy_plan(plan);
kml_fft_free(n);
kml_fft_free(in);
kml_fft_free(out);
/*
* out = {1.280000e+02, 8.000000e+01, 9.600000e+01, 1.760000e+02,
* 1.440000e+02, 1.280000e+02, 1.120000e+02, 9.600000e+01}
*/
Fortran interface:
INTEGER(C_INT) :: RANK = 2
INTEGER(C_INT) :: N(2)
REAL(C_DOUBLE), DIMENSION(6, 2) :: INIT
DATA N/2, 3/
TYPE(KML_FFT_COMPLEX), POINTER :: IN
REAL(C_DOUBLE), POINTER :: OUT
TYPE(C_PTR) :: PIN, POUT
INTEGER(C_SIZE_T) :: CSIZE, RSIZE
CSIZE = N(1) * (N(2) / 2 + 1)
RSIZE = N(1) * N(2)
PIN = KML_FFT_MALLOC(SIZEOF(16 * CSIZE))
POUT = KML_FFT_MALLOC(8 * RSIZE)
CALL C_F_POINTER(PIN, IN, SHAPE=[CSIZE])
CALL C_F_POINTER(POUT, OUT, SHAPE=[RSIZE])
DATA INIT/120, 8, 0, 0, 0, -8, 0, 8, 0, 16, 16, 8/
INTEGER :: I
DO WHILE(I <= CSIZE)
IN(I)%R = INIT(I, 0)
IN(I)%I = INIT(I, 1)
END DO
TYPE(C_PTR) :: PLAN
PLAN = KML_FFT_PLAN_DFT_C2R(RANK, N, IN, OUT, KML_FFT_ESTIMATE)
CALL KML_FFT_EXECUTE_DFT_C2R(PLAN, IN, OUT)
CALL KML_FFT_DESTROY_PLAN(PLAN)
CALL KML_FFT_FREE(PIN)
CALL KML_FFT_FREE(POUT)
!
! OUT = /1.280000E+02, 8.000000E+01, 9.600000E+01, 1.760000E+02,
! 1.440000E+02, 1.280000E+02, 1.120000E+02, 9.600000E+01/
!