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 Complex-by-Complex Multiplication CMSIS-DSP: Complex-by-Complex Multiplication
CMSIS-DSP  Version 1.7.0
CMSIS DSP Software Library

Functions

void arm_cmplx_mult_cmplx_f32 (const float32_t *pSrcA, const float32_t *pSrcB, float32_t *pDst, uint32_t numSamples)
Floating-point complex-by-complex multiplication. More...

void arm_cmplx_mult_cmplx_q15 (const q15_t *pSrcA, const q15_t *pSrcB, q15_t *pDst, uint32_t numSamples)
Q15 complex-by-complex multiplication. More...

void arm_cmplx_mult_cmplx_q31 (const q31_t *pSrcA, const q31_t *pSrcB, q31_t *pDst, uint32_t numSamples)
Q31 complex-by-complex multiplication. More...

Description

Multiplies a complex vector by another complex vector and generates a complex result. The data in the complex arrays is stored in an interleaved fashion (real, imag, real, imag, ...). The parameter numSamples represents the number of complex samples processed. The complex arrays have a total of 2*numSamples real values.

The underlying algorithm is used:

for (n = 0; n < numSamples; n++) {
pDst[(2*n)+0] = pSrcA[(2*n)+0] * pSrcB[(2*n)+0] - pSrcA[(2*n)+1] * pSrcB[(2*n)+1];
pDst[(2*n)+1] = pSrcA[(2*n)+0] * pSrcB[(2*n)+1] + pSrcA[(2*n)+1] * pSrcB[(2*n)+0];
}

There are separate functions for floating-point, Q15, and Q31 data types.

Function Documentation

void arm_cmplx_mult_cmplx_f32 ( const float32_t pSrcA,
const float32_t pSrcB,
float32_t pDst,
uint32_t  numSamples
)
Parameters
[in]pSrcApoints to first input vector
[in]pSrcBpoints to second input vector
[out]pDstpoints to output vector
[in]numSamplesnumber of samples in each vector
Returns
none
void arm_cmplx_mult_cmplx_q15 ( const q15_t pSrcA,
const q15_t pSrcB,
q15_t pDst,
uint32_t  numSamples
)
Parameters
[in]pSrcApoints to first input vector
[in]pSrcBpoints to second input vector
[out]pDstpoints to output vector
[in]numSamplesnumber of samples in each vector
Returns
none
Scaling and Overflow Behavior
The function implements 1.15 by 1.15 multiplications and finally output is converted into 3.13 format.
void arm_cmplx_mult_cmplx_q31 ( const q31_t pSrcA,
const q31_t pSrcB,
q31_t pDst,
uint32_t  numSamples
)
Parameters
[in]pSrcApoints to first input vector
[in]pSrcBpoints to second input vector
[out]pDstpoints to output vector
[in]numSamplesnumber of samples in each vector
Returns
none
Scaling and Overflow Behavior
The function implements 1.31 by 1.31 multiplications and finally output is converted into 3.29 format. Input down scaling is not required.