HANNING function is used to create a "window" for Fourier Transform
filtering. It can be used to create both Hanning and Hamming windows.
This routine is written in the IDL language. Its source code can be found in the file
subdirectory of the IDL distribution.
Result = HANNING(
The number of columns in the resulting array.
The number of rows in the resulting array.
Set this keyword equal to the width parameter of a generalized Hamming window. ALPHA must be in the range of 0.5 to 1.0. If ALPHA = 0.5 (the default) the function is called a "Hanning" window. If ALPHA = 0.54, the result is called a "Hamming" window.