# Vector ScaleBasic Math Functions

## Functions

void arm_scale_f32 (float32_t *pSrc, float32_t scale, float32_t *pDst, uint32_t blockSize)
Multiplies a floating-point vector by a scalar.

void arm_scale_q15 (q15_t *pSrc, q15_t scaleFract, int8_t shift, q15_t *pDst, uint32_t blockSize)
Multiplies a Q15 vector by a scalar.

void arm_scale_q31 (q31_t *pSrc, q31_t scaleFract, int8_t shift, q31_t *pDst, uint32_t blockSize)
Multiplies a Q31 vector by a scalar.

void arm_scale_q7 (q7_t *pSrc, q7_t scaleFract, int8_t shift, q7_t *pDst, uint32_t blockSize)
Multiplies a Q7 vector by a scalar.

## Description

Multiply a vector by a scalar value. For floating-point data, the algorithm used is:

```    pDst[n] = pSrc[n] * scale,   0 <= n < blockSize.
```

In the fixed-point Q7, Q15, and Q31 functions, `scale` is represented by a fractional multiplication `scaleFract` and an arithmetic shift `shift`. The shift allows the gain of the scaling operation to exceed 1.0. The algorithm used with fixed-point data is:

```    pDst[n] = (pSrc[n] * scaleFract) << shift,   0 <= n < blockSize.
```

The overall scale factor applied to the fixed-point data is

```    scale = scaleFract * 2^shift.
```

The functions support in-place computation allowing the source and destination pointers to reference the same memory buffer.

## Function Documentation

 void arm_scale_f32 ( float32_t * `pSrc, ` float32_t `scale, ` float32_t * `pDst, ` uint32_t `blockSize ` )
Parameters
 [in] `*pSrc` points to the input vector [in] `scale` scale factor to be applied [out] `*pDst` points to the output vector [in] `blockSize` number of samples in the vector
Returns
none.

References blockSize.

Referenced by arm_dct4_f32(), and main().

 void arm_scale_q15 ( q15_t * `pSrc, ` q15_t `scaleFract, ` int8_t `shift, ` q15_t * `pDst, ` uint32_t `blockSize ` )
Parameters
 [in] `*pSrc` points to the input vector [in] `scaleFract` fractional portion of the scale value [in] `shift` number of bits to shift the result by [out] `*pDst` points to the output vector [in] `blockSize` number of samples in the vector
Returns
none.

Scaling and Overflow Behavior:

The input data `*pSrc` and `scaleFract` are in 1.15 format. These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format.

References __PKHBT, __SIMD32, and blockSize.

 void arm_scale_q31 ( q31_t * `pSrc, ` q31_t `scaleFract, ` int8_t `shift, ` q31_t * `pDst, ` uint32_t `blockSize ` )
Parameters
 [in] `*pSrc` points to the input vector [in] `scaleFract` fractional portion of the scale value [in] `shift` number of bits to shift the result by [out] `*pDst` points to the output vector [in] `blockSize` number of samples in the vector
Returns
none.

Scaling and Overflow Behavior:

The input data `*pSrc` and `scaleFract` are in 1.31 format. These are multiplied to yield a 2.62 intermediate result and this is shifted with saturation to 1.31 format.

References blockSize.

Referenced by main().

 void arm_scale_q7 ( q7_t * `pSrc, ` q7_t `scaleFract, ` int8_t `shift, ` q7_t * `pDst, ` uint32_t `blockSize ` )
Parameters
 [in] `*pSrc` points to the input vector [in] `scaleFract` fractional portion of the scale value [in] `shift` number of bits to shift the result by [out] `*pDst` points to the output vector [in] `blockSize` number of samples in the vector
Returns
none.

Scaling and Overflow Behavior:

The input data `*pSrc` and `scaleFract` are in 1.7 format. These are multiplied to yield a 2.14 intermediate result and this is shifted with saturation to 1.7 format.

References __PACKq7, __SIMD32, and blockSize.