Complex Magnitude

Functions
void	arm_cmplx_mag_f16 (const float16_t *pSrc, float16_t *pDst, uint32_t numSamples)
	Floating-point complex magnitude.
void	arm_cmplx_mag_f32 (const float32_t *pSrc, float32_t *pDst, uint32_t numSamples)
	Floating-point complex magnitude.
void	arm_cmplx_mag_f64 (const float64_t *pSrc, float64_t *pDst, uint32_t numSamples)
	Floating-point complex magnitude.
void	arm_cmplx_mag_fast_q15 (const q15_t *pSrc, q15_t *pDst, uint32_t numSamples)
	Q15 complex magnitude.
void	arm_cmplx_mag_q15 (const q15_t *pSrc, q15_t *pDst, uint32_t numSamples)
	Q15 complex magnitude.
void	arm_cmplx_mag_q31 (const q31_t *pSrc, q31_t *pDst, uint32_t numSamples)
	Q31 complex magnitude.

Description

Computes the magnitude of the elements of a complex data vector.

The pSrc points to the source data and pDst points to the where the result should be written. numSamples specifies the number of complex samples in the input array and the data is stored in an interleaved fashion (real, imag, real, imag, ...). The input array has a total of 2*numSamples values; the output array has a total of numSamples values.

The underlying algorithm is used:

for (n = 0; n < numSamples; n++) {
    pDst[n] = sqrt(pSrc[(2*n)+0]^2 + pSrc[(2*n)+1]^2);
}

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

Function Documentation

arm_cmplx_mag_f16()

void arm_cmplx_mag_f16	(	const float16_t *	pSrc,
		float16_t *	pDst,
		uint32_t	numSamples
	)

Floating-point complex magnitude.

Parameters

[in]	pSrc	points to input vector
[out]	pDst	points to output vector
[in]	numSamples	number of samples in each vector

arm_cmplx_mag_f32()

void arm_cmplx_mag_f32	(	const float32_t *	pSrc,
		float32_t *	pDst,
		uint32_t	numSamples
	)

Floating-point complex magnitude.

Parameters

[in]	pSrc	points to input vector
[out]	pDst	points to output vector
[in]	numSamples	number of samples in each vector

arm_cmplx_mag_f64()

void arm_cmplx_mag_f64	(	const float64_t *	pSrc,
		float64_t *	pDst,
		uint32_t	numSamples
	)

Floating-point complex magnitude.

Parameters

[in]	pSrc	points to input vector
[out]	pDst	points to output vector
[in]	numSamples	number of samples in each vector

arm_cmplx_mag_fast_q15()

void arm_cmplx_mag_fast_q15	(	const q15_t *	pSrc,
		q15_t *	pDst,
		uint32_t	numSamples
	)

Q15 complex magnitude.

Parameters

[in]	pSrc	points to input vector
[out]	pDst	points to output vector
[in]	numSamples	number of samples in each vector

Scaling and Overflow Behavior

The function implements 1.15 by 1.15 multiplications and finally output is converted into 2.14 format. Fast functions are less accurate. This function will tend to clamp to 0 the too small values. So sqrt(x*x) = x will not always be true.

arm_cmplx_mag_q15()

void arm_cmplx_mag_q15	(	const q15_t *	pSrc,
		q15_t *	pDst,
		uint32_t	numSamples
	)

Q15 complex magnitude.

Parameters

[in]	pSrc	points to input vector
[out]	pDst	points to output vector
[in]	numSamples	number of samples in each vector

Scaling and Overflow Behavior

The function implements 1.15 by 1.15 multiplications and finally output is converted into 2.14 format.

arm_cmplx_mag_q31()

void arm_cmplx_mag_q31	(	const q31_t *	pSrc,
		q31_t *	pDst,
		uint32_t	numSamples
	)

Q31 complex magnitude.

Parameters

[in]	pSrc	points to input vector
[out]	pDst	points to output vector
[in]	numSamples	number of samples in each vector

Scaling and Overflow Behavior

The function implements 1.31 by 1.31 multiplications and finally output is converted into 2.30 format. Input down scaling is not required.