fshift

Shifts the elements of an array by a (possibly non-integer) given number of elements.

FSHIFT shifts the elements in a vector by a given number of elements, as CIRCSHIFT does. However, a non-integer shift value can be used, in which case the elements are shifted along the perfect (sinc-based) interpolation of the periodisation of the vector. For integer shift values, FSHIFT is equivalent to CIRCSHIFT to machine precision.
The syntax to FSHIFT is slightly different from CIRCSHIFT (FSHIFT expects only vectors for its first argument and a scalar for its second argument). Also, the second arguments produces a shift in the opposite direction of CIRCSHIFT to be consistent with the usual statement of the shift property of the Fourier transform.
FSHIFT works by introducing a linear phase into the vector's DFT. As such, if there is a discontinuity between the first and last elements of the input vector, the output vector may present significant ringing.