---
title: kml_fft(f)_mpi_local_size_transposed_ext
description: "描述了使能box_order后，本地进程数据的大小和位置，以及计算所需分配的空间。"
url: https://www.hikunpeng.com/document/detail/zh/kunpenghpcs/hpckit/devg/kunpengaccel_kml_0413.html
sourcePath: /source/zh/kunpenghpcs/hpckit/devg/kunpengaccel_kml_0413.html
indexId: 4c320812392a5a1f74d1b1b10f9fbc844b1db096f8d1d6ed0bcea792fea304a661
---
# kml_fft(f)_mpi_local_size_transposed_ext

描述了使能box_order后，本地进程数据的大小和位置，以及计算所需分配的空间。

#### 接口定义

C interface：

ptrdiff_t kml_fft_mpi_local_size_transposed_ext(int rank, const ptrdiff_t *n, MPI_Comm comm, enum SCALFFT_DECOMPOSE_TYPE_E decomp_type, const int *order, ptrdiff_t *low, ptrdiff_t *high);

ptrdiff_t kml_fftf_mpi_local_size_transposed_ext(int rank, const ptrdiff_t *n, MPI_Comm comm, enum SCALFFT_DECOMPOSE_TYPE_E decomp_type, const int *order, ptrdiff_t *low, ptrdiff_t *high);


#### 返回值

函数返回一个ptrdiff_t类型的值，表示要分配的buffer元素个数，成功则返回值大于等于0，失败返回-1。


#### 参数


**表1 参数定义**

| 参数名 | 数据类型 | 描述 | 输入/输出 |
| --- | --- | --- | --- |
| rank | int | 进程号 | 输入 |
| n | ptrdiff\_t \* | 待处理数据第1个维度大小，约束：n0 ≥ 1 | 输入 |
| comm | MPI\_Comm | 通信域 | 输入 |
| decomp\_type | enum SCALFFT\_DECOMPOSE\_TYPE\_E | 分解算法，SCALFFT\_DECOMPOSE\_TYPE\_SLAB，SCALFFT\_DECOMPOSE\_TYPE\_PENCIL，SCALFFT\_DECOMPOSE\_TYPE\_BRICK | 输入 |
| order | int \* | 是长度为3的一维数组，输入数据维度的顺序，取值为0、1、2的任意顺序组合，输入NULL，默认order为0、1、2。 | 输入 |
| low | ptrdiff\_t \* | 本地数据起点 | 输出 |
| high | ptrdiff\_t \* | 本地数据终点 | 输出 |


#### 依赖

C: "kfft-mpi.h"


#### 示例

C interface：

```
const int n0 = 4, n1 = 4, n2 = 4;
kml_fft_plan plan;
int provided;
MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &provided);
MPI_Comm comm = MPI_COMM_WORLD;
kml_fft_complex *in = NULL;
kml_fft_complex *out = NULL;
/* get local data size and allocate */
ptrdiff_t in_low[3] = {0};
ptrdiff_t in_high[3] = {0};
ptrdiff_t out_low[3] = {0};
ptrdiff_t out_high[3] = {0};
ptrdiff_t n[3] = {n0, n1, n2};
int in_order[3] = {0, 1, 2};
int out_order[3] = {1, 2, 0};
ptrdiff_t in_alloc_local = kml_fft_mpi_local_size_transposed_ext(3, n, comm, SCALFFT_DECOMPOSE_TYPE_PENCIL, in_order, in_low, in_high);
if (in_alloc_local == -1) {
printf("[%s][%d] allocate size fail.\n", __func__, __LINE__);
}
ptrdiff_t out_alloc_local = kml_fft_mpi_local_size_transposed_ext(3, n, comm, SCALFFT_DECOMPOSE_TYPE_PENCIL, out_order, out_low, out_high);
if (out_alloc_local == -1) {
printf("[%s][%d] allocate size fail.\n", __func__, __LINE__);
}
in = (kml_fft_complex *)kml_fft_malloc(sizeof(kml_fft_complex) * in_alloc_local);
if (in == NULL) {
printf("[%s][%d] malloc memory fail.\n", __func__, __LINE__);
}
out = (kml_fft_complex *)kml_fft_malloc(sizeof(kml_fft_complex) * out_alloc_local);
if (out == NULL) {
printf("[%s][%d] malloc memory fail.\n", __func__, __LINE__);
}
/* create plan */
int in_low_int[3] = {in_low[0], in_low[1], in_low[2]};
int in_high_int[3] = {in_high[0], in_high[1], in_high[2]};
int out_low_int[3] = {out_low[0], out_low[1], out_low[2]};
int out_high_int[3] = {out_high[0], out_high[1], out_high[2]};
kml_fft_mpi_options options = {
.a2a_algo    = A2A_ALGO_AUTO_TUNING,
.decomp_type = SCALFFT_DECOMPOSE_TYPE_PENCIL
};
plan = kml_fft_mpi_plan_create(BACKEND_KFFT, in_low_int, in_high_int, in_order, out_low_int, out_high_int, out_order, comm, options);
/* execute plan */
int scale = 0;
kml_fft_mpi_execute_dft_ext(plan, in, out, scale, KML_FFT_FORWARD);
kml_fft_mpi_execute_dft_ext(plan, out, in, scale, KML_FFT_BACKWARD);
// kml_fft_mpi_forward_c2c(plan, in, out, scale);
// kml_fft_mpi_backward_c2c(plan, out, in, scale);
kml_fft_destroy_plan_ext(plan);
kml_fft_free(in);
kml_fft_free(out);
MPI_Finalize();
```