CMSIS DSP Software Library: Mean

Functions

# Mean
[Statistics Functions]

## Functions

void | arm_mean_f32 (float32_t *pSrc, uint32_t blockSize, float32_t *pResult)
void | arm_mean_q31 (q31_t *pSrc, uint32_t blockSize, q31_t *pResult)
void | arm_mean_q15 (q15_t *pSrc, uint32_t blockSize, q15_t *pResult)
void | arm_mean_q7 (q7_t *pSrc, uint32_t blockSize, q7_t *pResult)

## Detailed Description

Calculates the mean of the input vector. Mean is defined as the average of the elements in the vector. The underlying algorithm is used:

     	Result = (pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]) / blockSize;

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

## Function Documentation

void arm_mean_f32 | ( | float32_t * | pSrc,
|  | uint32_t | blockSize,
|  | float32_t * | pResult
| ) |  |

Mean value of a floating-point vector.

Parameters:

  [in] | *pSrc | points to the input vector
  [in] | blockSize | length of the input vector
  [out] | *pResult | mean value returned here

Returns:
  none.

Examples:
  arm_class_marks_example_f32.c.

Definition at line 64 of file arm_mean_f32.c.

void arm_mean_q31 | ( | q31_t * | pSrc,
|  | uint32_t | blockSize,
|  | q31_t * | pResult
| ) |  |

Mean value of a Q31 vector.

Parameters:

  [in] | *pSrc | points to the input vector
  [in] | blockSize | length of the input vector
  [out] | *pResult | mean 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 and is accumulated in a 64-bit accumulator in 33.31 format. There is no risk of internal overflow with this approach, and the full precision of intermediate result is preserved. Finally, the accumulator is truncated to yield a result of 1.31 format.

Definition at line 61 of file arm_mean_q31.c.

void arm_mean_q15 | ( | q15_t * | pSrc,
|  | uint32_t | blockSize,
|  | q15_t * | pResult
| ) |  |

Mean value of a Q15 vector.

Parameters:

  [in] | *pSrc | points to the input vector
  [in] | blockSize | length of the input vector
  [out] | *pResult | mean value returned here

Returns:
  none.

Scaling and Overflow Behavior:

  The function is implemented using a 32-bit internal accumulator. The input is represented in 1.15 format and is accumulated in a 32-bit accumulator in 17.15 format. There is no risk of internal overflow with this approach, and the full precision of intermediate result is preserved. Finally, the accumulator is saturated and truncated to yield a result of 1.15 format.

Definition at line 61 of file arm_mean_q15.c.

void arm_mean_q7 | ( | q7_t * | pSrc,
|  | uint32_t | blockSize,
|  | q7_t * | pResult
| ) |  |

Mean value of a Q7 vector.

Parameters:

  [in] | *pSrc | points to the input vector
  [in] | blockSize | length of the input vector
  [out] | *pResult | mean 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 and is accumulated in a 32-bit accumulator in 25.7 format. There is no risk of internal overflow with this approach, and the full precision of intermediate result is preserved. Finally, the accumulator is truncated to yield a result of 1.7 format.

Definition at line 61 of file arm_mean_q7.c.

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