---
title: vDSP_vgenpD
framework: accelerate
role: symbol
role_heading: Function
path: accelerate/vdsp_vgenpd
---

# vDSP_vgenpD

Generates the double-precision linearly interpolated values of a vector at the specified indices.

## Declaration

```occ
extern void vDSP_vgenpD(const double *__A, vDSP_Stride __IA, const double *__B, vDSP_Stride __IB, double *__C, vDSP_Stride __IC, vDSP_Length __N, vDSP_Length __M);
```

## Parameters

- `__A`: The input vector that defines the values that the function interpolates.
- `__IA`: The distance between the elements in the values vector.
- `__B`: The input vector that defines the indices at which the function interpolates.
- `__IB`: The distance between the elements in the indices vector.
- `__C`: The output vector.
- `__IC`: The distance between the elements in the output vector.
- `__N`: The number of elements that the function processes.
- `__M`: The number of elements in the values and indices input vectors.

## Mentioned in

Using linear interpolation to construct new data points

## Discussion

Discussion The following code creates a five-element vector from two values using linear interpolation. The last index in indices determines the length of the operation result.     let values: [Double] = [0, 100]     let indices: [Double] = [0, 4]          let n = Int(indices.last! + 1)     let m = values.count          let stride = 1          let interpolatedValues = [Double](unsafeUninitializedCapacity: n) {         buffer, initializedCount in                  vDSP_vgenpD(values, stride,                     indices, stride,                     buffer.baseAddress!, stride,                     vDSP_Length(n),                     vDSP_Length(m))                  initializedCount = n     }          // Prints "[0.0, 25.0, 50.0, 75.0, 100.0]".     print(interpolatedValues)

## See Also

### Vector generation by extrapolation and interpolation

- [vDSP_vgenp](accelerate/vdsp_vgenp.md)