This is documentation for an old release of SciPy (version 0.10.1). Read this page in the documentation of the latest stable release (version 1.15.1).
Shift periodic sequence x by a: y(u) = x(u+a).
If x_j and y_j are Fourier coefficients of periodic functions x and y, respectively, then
y_j = exp(j*a*2*pi/period*sqrt(-1)) * x_f