PERIODOGRAM(ordinates,filter,abscissae,interpolation,number)
ordinates: ordinates of the given data
filter: windowing function to be used, defaults to no filter
abscissae: abscissae of the given data, defaults to regularly spaced abscissae
interpolation: method of interpolation, defaults to none
number: number of interpolated data points
If an interpolation method is used, the number of returned values is one less than the number of targets and the targets values must be given in increasing order.
The output consists always of one column of numbers.
Possible interpolation methods are:
0: linear;
1: linear with averaging;
2: staircase;
3: staircase with averaging;
4: natural cubic spline;
5: natural cubic spline with averaging.
Possible window functions are:
0: no filter (rectangular window)
1: Bartlett (triangular window)
2: Hahn (cosine window)
3: Welch (parabolic window)
Strings and empty cells in abscissae and ordinates are ignored. If several target data are provided they must be in the same column in consecutive cells.