IDL Wavelet Toolkit User's Guide

Chapter 4: IDL Wavelet Toolkit Reference 67NSCALESet this keyword to a scalar value giving the total number of scale values to use forthe wavelet transform. The default is [log 2 (N/START_SCALE)]/DSCALE+1.PADSet this keyword to force Array to be padded with zeroes before computing thetransform. Enough zeroes are added to make the total length of Array equal to thenext-higher power-of-two greater than 2N. Padding with zeroes prevents wraparoundof the Array and speeds up the fast Fourier transform.NotePadding with zeroes reduces, but does not eliminate, edge effects caused by thediscontinuities at the start and end of the data.SCALESet this keyword to a named variable in which to return the scale values used for thecontinuous wavelet transform. The SCALE values range from START_SCALE up toSTART_SCALE·2^[(NSCALE–1)DSCALE].START_SCALESet this keyword to a scalar value giving the starting scale, in non-dimensional units.The default is 2, which gives a starting scale that is twice the spacing between Arrayelements.ReferenceTorrence and Compo, 1998: A Practical Guide to Wavelet Analysis. Bull. Amer.Meteor. Soc., 79, 61–78.Example; Assume we have monthly random data.n = 500dt = 1d/12 ; time samplingseed = 999data = RANDOMN(seed, n)time = 1960 + dt*FINDGEN(n); Compute the wavelet transform and the power.wave = WV_CWT(data, 'Morlet', 6, /PAD, SCALE=scales)IDL Wavelet ToolkitWV_CWT