---
title: vDSP_maxmgv
framework: Kernel
role: symbol
role_heading: Function
platforms: [macOS 10.4+]
path: kernel/1532187-vdsp_maxmgv
---

# vDSP_maxmgv

Calculates the maximum magnitude in a single-precision vector.

## Declaration

```occ
void vDSP_maxmgv(const float *__A, vDSP_Stride __IA, float *__C, vDSP_Length __N);
```

## Parameters

- `__A`: The single-precision real input vector A.
- `__I`: The stride for input vector A.
- `__C`: The single-precsion output scalar.
- `__N`: The number of elements to process. If N is zero (0), this function returns -INFINITY.

## Discussion

Discussion This function calculates the maximum magnitude of the first N elements of A and writes the result to C:

The operation is:  *C = -INFINITY; for (n = 0; n < N; ++n)     if (*C < |A[n*I]|)         *C = |A[n*I]|; The following code shows an example of using vDSP_maxmgv. let stride = vDSP_Stride(1)

let a: [Float] = [-1.5, 2.25, 3.6,                   0.2, -0.1, -4.3] let n = vDSP_Length(a.count)

var c: Float = .nan

vDSP_maxmgv(a,             stride,             &c,             n)

print("max magnitude", c) // Prints "max magnitude 4.3".