vDSP_vpoly

Declaration

extern void vDSP_vpoly(const float *__A, vDSP_Stride __IA, const float *__B, vDSP_Stride __IB, float *__C, vDSP_Stride __IC, vDSP_Length __N, vDSP_Length __P);

Parameters

• __A:

  A vector that contains __P + 1 coefficients.

• __IA:

  The distance between the elements in the input vector A.

• __B:

  A vector that contains the variables.

• __IB:

  The distance between the elements in the input vector B.

• __C:

  A vector that receives the result of the calculation.

• __IC:

  The distance between the elements in the output vector C.

• __N:

  The number of variables that the function processes to produce the same number of output elements.

• __P:

  The degree of the polynomial.

Discussion

For example, the following code evaluates the polynomial with the coefficients [10.0, 20.0, 30.0] and the variables [7.0, 5.0]:

    let stride = 1
    
    let coefficients: [Float] = [10, 20, 30]
    let variables: [Float] = [7, 5]
    
    let result = [Float](
        unsafeUninitializedCapacity: variables.count) {
            buffer, initializedCount in
            
            vDSP_vpoly(coefficients, stride, 
                       variables, stride,
                       buffer.baseAddress!, stride,
                       vDSP_Length(variables.count),
                       vDSP_Length(coefficients.count - 1))
            
            initializedCount = 2
        }
   
    // Prints "[660.0, 380.0]".
    //    result[0] = (10 * 7²) + (20 * 7¹) + (30 * 7⁰) = 660
    //    result[1] = (10 * 5²) + (20 * 5¹) + (30 * 5⁰) = 380
    print(result)