CMSIS-DSP: Power

| CMSIS-DSP Version 1.8.0 CMSIS DSP Software Library

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Functions
Power
Statistics Functions

## Functions

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.

## Function Documentation

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.