ChapterW_cosine

W_cosine

Cosine window.

Loading LOADSUB ALL FROM "W_COSINE.HTS"

or LOADSUB FROM "MATHLIB.HTS"

or LOADSUB W_cosine FROM "MATHLIB.HTS"

Usage REAL A(*),B(*)

REAL R

CALL W_cosine(A(*),R,B(*))

Description

W_cosine multiplies the sequence in array A by a cosine window function of parameter r and returns the product in array B. Array A is unmodified. R is the peak-to-peak amplitude of the cosine portion of the window; it must be between 0 and 1, inclusive. If N is the number of elements in the array A and k is the position in the array B, the formula for the window function, wk, is

In the above formula, k ranges in value from 0 to N - 1.

If the array B contains more elements than A, the extra elements in B are unmodified.

Cosine windows for N=128

Special cases of the cosine window are the Hamming and Hanning windows; these are available as separate subroutines.

Errors

W_cosine causes an HTBasic error if its arguments are not of the types listed in the USAGE section, above, if r is not between 0 and 1, inclusive, or if B contains fewer elements than A.

See Also

Waveform, W_bartlett, W_blackman, W_hamming, W_hanning