Power

Functions
void	arm_power_f16 (const float16_t *pSrc, uint32_t blockSize, float16_t *pResult)
	Sum of the squares of the elements of a floating-point vector. More...
void	arm_power_f32 (const float32_t *pSrc, uint32_t blockSize, float32_t *pResult)
	Sum of the squares of the elements of a floating-point vector. More...
void	arm_power_q15 (const q15_t *pSrc, uint32_t blockSize, q63_t *pResult)
	Sum of the squares of the elements of a Q15 vector. More...
void	arm_power_q31 (const q31_t *pSrc, uint32_t blockSize, q63_t *pResult)
	Sum of the squares of the elements of a Q31 vector. More...
void	arm_power_q7 (const q7_t *pSrc, uint32_t blockSize, q31_t *pResult)
	Sum of the squares of the elements of a Q7 vector. More...

Description

Calculates the sum of the squares of the elements in the input vector. The underlying algorithm is used:

    Result = pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + pSrc[2] * pSrc[2] + ... + pSrc[blockSize-1] * pSrc[blockSize-1];

There are separate functions for floating point, Q31, Q15, and Q7 data types.

Since the result is not divided by the length, those functions are in fact computing something which is more an energy than a power.

Function Documentation

void arm_power_f16	(	const float16_t *	pSrc,
		uint32_t	blockSize,
		float16_t *	pResult
	)

Parameters

[in]	pSrc	points to the input vector
[in]	blockSize	number of samples in input vector
[out]	pResult	sum of the squares value returned here

Returns

none

void arm_power_f32	(	const float32_t *	pSrc,
		uint32_t	blockSize,
		float32_t *	pResult
	)

Parameters

[in]	pSrc	points to the input vector
[in]	blockSize	number of samples in input vector
[out]	pResult	sum of the squares value returned here

Returns

none

void arm_power_q15	(	const q15_t *	pSrc,
		uint32_t	blockSize,
		q63_t *	pResult
	)

Parameters

[in]	pSrc	points to the input vector
[in]	blockSize	number of samples in input vector
[out]	pResult	sum of the squares value returned here

Returns

none

Scaling and Overflow Behavior

The function is implemented using a 64-bit internal accumulator. The input is represented in 1.15 format. Intermediate multiplication yields a 2.30 format, and this result is added without saturation to a 64-bit accumulator in 34.30 format. With 33 guard bits in the accumulator, there is no risk of overflow, and the full precision of the intermediate multiplication is preserved. Finally, the return result is in 34.30 format.

void arm_power_q31	(	const q31_t *	pSrc,
		uint32_t	blockSize,
		q63_t *	pResult
	)

Parameters

[in]	pSrc	points to the input vector
[in]	blockSize	number of samples in input vector
[out]	pResult	sum of the squares value returned here

Returns

none

Scaling and Overflow Behavior

The function is implemented using a 64-bit internal accumulator. The input is represented in 1.31 format. Intermediate multiplication yields a 2.62 format, and this result is truncated to 2.48 format by discarding the lower 14 bits. The 2.48 result is then added without saturation to a 64-bit accumulator in 16.48 format. With 15 guard bits in the accumulator, there is no risk of overflow, and the full precision of the intermediate multiplication is preserved. Finally, the return result is in 16.48 format.

void arm_power_q7	(	const q7_t *	pSrc,
		uint32_t	blockSize,
		q31_t *	pResult
	)

Parameters

[in]	pSrc	points to the input vector
[in]	blockSize	number of samples in input vector
[out]	pResult	sum of the squares value returned here

Returns

none

Scaling and Overflow Behavior

The function is implemented using a 32-bit internal accumulator. The input is represented in 1.7 format. Intermediate multiplication yields a 2.14 format, and this result is added without saturation to an accumulator in 18.14 format. With 17 guard bits in the accumulator, there is no risk of overflow, and the full precision of the intermediate multiplication is preserved. Finally, the return result is in 18.14 format.