---
title: cvmag
description: "复数向量求模长运算。"
url: https://www.hikunpeng.com/document/detail/zh/kunpengaccel/system-lib/ug-kvsip/kunpengaccel_kvsip_06_0046.html
sourcePath: /source/zh/kunpengaccel/system-lib/ug-kvsip/kunpengaccel_kvsip_06_0046.html
indexId: 91efdfa6d940c49bcbfa971ac98568c68d2eb8ecd40a3d1fffaf7f46e4f25efe75
---
# cvmag

复数向量求模长运算。

函数接口声明如下：

float型函数的操作：

void (vsip_cvmag_f)(const vsip_cvview_f *a, const vsip_vview_f *r);

#### 参数

| 参数名 | 描述 | 取值范围 | 输入/输出 |
| --- | --- | --- | --- |
| a | 指向源复数向量的指针。 | 非空 | 输入 |
| r | 指向目的向量的指针。 | 非空 | 输出 |


#### 异常输入

空指针输入时，函数直接返回。


#### 示例

```
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "kvsip.h"
#include "vsip.h"
#include "vsip_type.h"

#define BUFFER_SIZE_T 10
void CvmagExample()
{
    float src[BUFFER_SIZE_T] = {1.64f, 1.63f, -1.09f, 0.71f, -3.20f, -0.43f, 0.41f, -4.83f, 5.36f, -4.40f};
    float dst[BUFFER_SIZE_T / 2];
    int64_t cvLen = BUFFER_SIZE_T / 2;
    int64_t stride = 1;
    uint64_t offset = 0;

    vsip_cblock_f *block_a = vsip_cblockbind_f(src, NULL, cvLen, VSIP_MEM_NONE);
    vsip_block_f *block_r = vsip_blockbind_f(dst, cvLen, VSIP_MEM_NONE);

    vsip_cvview_f *a = vsip_cvbind_f(block_a, offset, stride, cvLen);
    vsip_cblockadmit_f(block_a, VSIP_TRUE);
    vsip_vview_f *r = vsip_vbind_f(block_r, offset, stride, BUFFER_SIZE_T);
    vsip_blockadmit_f(block_r, VSIP_TRUE);

    vsip_cvmag_f(a, r);

    vsip_cvalldestroy_f(a);
    vsip_valldestroy_f(r);


    printf("src:\n");
    for (int32_t i = 0; i < cvLen; ++i) {
        printf("%.2f ", src[i * 2]);
        printf("%.2f    ", src[i * 2 + 1]);
    }
    printf("\ndst:\n");
    for (int32_t i = 0; i < cvLen; ++i) {
        printf("%.2f    ", dst[i]);
    }
    printf("\n");
}

int main(void) {
    CvmagExample();
    return 0;
}
```

运行结果：

```
src:
1.64 1.63    -1.09 0.71    -3.20 -0.43    0.41 -4.83    5.36 -4.40
dst:
2.31    1.30    3.23    4.85    6.93
```