Routines (alphabetical) > Routines: C > CHEBYSHEV

# CHEBYSHEV

The CHEBYSHEV function returns the forward or reverse Chebyshev polynomial expansion of a set of data. Note: Results from this function are subject to roundoff error given discontinuous data.

This routine is written in the IDL language. Its source code can be found in the file `chebyshev.pro` in the `lib` subdirectory of the IDL distribution.

## Syntax

Result = CHEBYSHEV(D, N)

## Return Value

Returns the forward or reverse Chebyshev polynomial expansion of a set of data.

## Arguments

### D

A vector containing the values at the zeros of Chebyshev polynomial.

### N

A flag that, if set to -1, returns a set of Chebyshev polynomials. If set to +1, the original data is returned.

## Keywords

None.

## Version History

Original | Introduced

## See Also

FFT, WTN