Windowfunctions: Windowfunctions
In spectral: Common Methods of Spectral Data Analysis

Some typical windowfunctions are defined below:

win.cos(): cosine window
win.tukey(): Tukey window
win.hann(): Hann window
win.nutt(): Nutt window

A window function weights a given dataset in a way, that the new data set is coerced to be periodic. This method reduces the leakage effects of the discrete Fourier transform.

All window functions return a wighting vector with the same length as the provided data vector.

y <- 1:100
y_cos <- y * win.cos(y)
y_tuk <- y * win.tukey(y)
y_han <- y * win.hann(y)

# Plot the original data
plot(y,main="Effect of window functions")
legend("topleft",c("original","cos","tukey","han"),pch=c(1,16,17,18))
points(y_cos,pch=16)
points(y_tuk,pch=17)
points(y_han,pch=18)