CMSIS-DSP: Vector Dot Product

| CMSIS-DSP Version 1.4.7 CMSIS DSP Software Library

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Vector Dot Product
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## Functions

void | arm_dot_prod_f32 (float32_t *pSrcA, float32_t *pSrcB, uint32_t blockSize, float32_t *result)
| Dot product of floating-point vectors.
void | arm_dot_prod_q15 (q15_t *pSrcA, q15_t *pSrcB, uint32_t blockSize, q63_t *result)
| Dot product of Q15 vectors.
void | arm_dot_prod_q31 (q31_t *pSrcA, q31_t *pSrcB, uint32_t blockSize, q63_t *result)
| Dot product of Q31 vectors.
void | arm_dot_prod_q7 (q7_t *pSrcA, q7_t *pSrcB, uint32_t blockSize, q31_t *result)
| Dot product of Q7 vectors.

## Description

Computes the dot product of two vectors. The vectors are multiplied element-by-element and then summed.

        sum = pSrcA[0]*pSrcB[0] + pSrcA[1]*pSrcB[1] + ... + pSrcA[blockSize-1]*pSrcB[blockSize-1]

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

## Function Documentation

void arm_dot_prod_f32 | ( | float32_t * | pSrcA,
|  | float32_t * | pSrcB,
|  | uint32_t | blockSize,
|  | float32_t * | result
| ) |  |

Parameters

  [in] | *pSrcA | points to the first input vector
  [in] | *pSrcB | points to the second input vector
  [in] | blockSize | number of samples in each vector
  [out] | *result | output result returned here

Returns
  none.

Examples:
  arm_variance_example_f32.c.

References blockSize.

Referenced by main().

void arm_dot_prod_q15 | ( | q15_t * | pSrcA,
|  | q15_t * | pSrcB,
|  | uint32_t | blockSize,
|  | q63_t * | result
| ) |  |

Parameters

  [in] | *pSrcA | points to the first input vector
  [in] | *pSrcB | points to the second input vector
  [in] | blockSize | number of samples in each vector
  [out] | *result | output result returned here

Returns
  none.

Scaling and Overflow Behavior:

  The intermediate multiplications are in 1.15 x 1.15 = 2.30 format and these results are added to a 64-bit accumulator in 34.30 format. Nonsaturating additions are used and given that there are 33 guard bits in the accumulator there is no risk of overflow. The return result is in 34.30 format.

References __SIMD32, and blockSize.

void arm_dot_prod_q31 | ( | q31_t * | pSrcA,
|  | q31_t * | pSrcB,
|  | uint32_t | blockSize,
|  | q63_t * | result
| ) |  |

Parameters

  [in] | *pSrcA | points to the first input vector
  [in] | *pSrcB | points to the second input vector
  [in] | blockSize | number of samples in each vector
  [out] | *result | output result returned here

Returns
  none.

Scaling and Overflow Behavior:

  The intermediate multiplications are in 1.31 x 1.31 = 2.62 format and these are 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. There are 15 guard bits in the accumulator and there is no risk of overflow as long as the length of the vectors is less than 2^16 elements. The return result is in 16.48 format.

References blockSize.

void arm_dot_prod_q7 | ( | q7_t * | pSrcA,
|  | q7_t * | pSrcB,
|  | uint32_t | blockSize,
|  | q31_t * | result
| ) |  |

Parameters

  [in] | *pSrcA | points to the first input vector
  [in] | *pSrcB | points to the second input vector
  [in] | blockSize | number of samples in each vector
  [out] | *result | output result returned here

Returns
  none.

Scaling and Overflow Behavior:

  The intermediate multiplications are in 1.7 x 1.7 = 2.14 format and these results are added to an accumulator in 18.14 format. Nonsaturating additions are used and there is no danger of wrap around as long as the vectors are less than 2^18 elements long. The return result is in 18.14 format.

References __SIMD32, and blockSize.