---
title: vDSP_vlint
framework: accelerate
role: symbol
role_heading: Function
path: accelerate/vdsp_vlint
---

# vDSP_vlint

Calculates the interpolation between the neighboring elements of a single-precision vector using the specified stride.

## Declaration

```occ
extern void vDSP_vlint(const float *__A, const float *__B, vDSP_Stride __IB, float *__C, vDSP_Stride __IC, vDSP_Length __N, vDSP_Length __M);
```

## Parameters

- `__A`: The single-precision input vector.
- `__B`: The vector that controls the interpolation. The integer part of each element in the control vector is the zero-based index of the first element of a pair of adjacent values in the source array. The fractional part defines the linear interpolation between the values at those indices.
- `__IB`: The stride between elements in the vector __B.
- `__C`: The single-precision output vector.
- `__IC`: The stride between elements in the vector __C.
- `__N`: The number of elements in the output vector.
- `__M`: The number of elements in the input vector.

## Mentioned in

Using linear interpolation to construct new data points

## Discussion

Discussion Performs the following operation: for (int n = 0; n < N; ++n){     float b = B[n*IB];     float index = trunc(b); // The integer part of B.     float alpha = b - index; // The fractional part of B.       float a0 = A[(int)index]; // The indexed A value.     float a1 = A[(int)index + 1]; // The next indexed A value.       C[n*IC] = a0 + (alpha * (a1 -a0)); // The interpolated value. } The function generates vector C by interpolating between neighboring values of vector A as controlled by vector B. The operation treats the integer portion of each element in B as the zero-based index of the first element of a pair of adjacent values in vector A. The function uses the fractional part of the value in B to calculate the corresponding element of C from the two adjacent values. The calculation doesn’t use the argument M. However, the integer parts of the values in B must be greater than or equal to zero and less than or equal to M - 2.

## See Also

### Single-Vector Linear Interpolation

- [Using linear interpolation to construct new data points](accelerate/using-linear-interpolation-to-construct-new-data-points.md)
- [vDSP_vlintD](accelerate/vdsp_vlintd.md)