csort sorts the rows of a complex matrix with respect to the absolute value of the complex numbers. If a column c is specified the rows of the matrix will be ordered with respect to the elements of column c in ascending (descending) order.
sorts with respect to either a real part of a column or an imaginary part of a column c. If 1 <= c <= cols(xr) it sorts after the real part of x, if cols(xr) < c <= cols(xr)+cols(xi) it sorts the imaginary part after column c-cols(xr).
Calculates the coefficient in applying a basis expansion by using Fourier series. In this case, it is assumed that the data unit can be expressed by a linear combination of finite terms of sine and cosine functions.