vDSP_mmul

Declaration

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

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