---
title: vDSP_mmul
framework: accelerate
role: symbol
role_heading: Function
path: accelerate/vdsp_mmul
---

# vDSP_mmul

Performs an out-of-place multiplication of two single-precision real matrices.

## Declaration

```occ
extern void vDSP_mmul(const float *__A, vDSP_Stride __IA, const float *__B, vDSP_Stride __IB, float *__C, vDSP_Stride __IC, vDSP_Length __M, vDSP_Length __N, vDSP_Length __P);
```

## Parameters

- `__A`: The M x P left-hand side input matrix.
- `__IA`: The distance between the elements in the left-hand side input matrix.
- `__B`: The P x N right-hand side input matrix.
- `__IB`: The distance between the elements in the right-hand side input matrix.
- `__C`: The M x N output matrix.
- `__IC`: The distance between the elements in the output matrix.
- `__M`: The number of rows in matrices A and C.
- `__N`: The number of columns in matrices B and C.
- `__P`: The number of columns in matrix A and the number of rows in matrix B.

## Discussion

Discussion The following code multiplies the matrices a and b, and writes the result to matrix c:     let m: vDSP_Length = 2     let n: vDSP_Length = 5     let p: vDSP_Length = 3          // `m` rows x `p` columns.     let a: [Float] = [ 1, 2, 3,                        4, 5, 6 ]          // `p` rows x `n` columns.     let b: [Float] = [ 10, 11, 12, 13, 14,                        15, 16, 17, 18, 19,                        20, 21, 22, 23, 24 ]                    // `m` rows x `n` columns.     var c = [Float](repeating: 0,                     count: Int(m * n))          let stride = 1          vDSP_mmul(a, stride,               b, stride,               &c, stride,               m,               n,               p)          // Prints:     // "[ 100.0, 106.0, 112.0, 118.0, 124.0,     //    235.0, 250.0, 265.0, 280.0, 295.0 ]".     print(c)

## See Also

### Multiplying real matrices

- [vDSP_mmulD](accelerate/vdsp_mmuld.md)