Not a long time ago I played with the decomposition of time series. This involved different tasks related to seasonality detection and autocorrelation. When I was implementing ACF (autocorrelation function), I, of course, wondered if I got it right.
Thus I needed test data, and that's why I've created this calculator. The idea was to take some defined function, like sine, distort it with some random noise and use distorted values in ACF calculator (and other related calculators), to see if calculator will be able to detect seasonality (which indeed presents in original function).
So here it goes. You should enter function of one variable, starting and ending values of this variable, number of points to generate and randomness parameter, where zero means no noise. Randomness is generated based on difference between current and previous values of the function.
The chart displays resulted distorted function along with the original function. You also have the option to dump generated values to csv data, so you can copy them and use as test data.