Hi, in my C-code I want to apply the gwyddion fft-transformation to SPM data.
the code sniplet is: data_field_fft_r = gwy_data_field_new_alike(data_field, TRUE); data_field_fft_i = gwy_data_field_new_alike(data_field, TRUE); gwy_data_field_2dfft(data_field,NULL,data_field_fft_r,data_field_fft_i,GWY_WINDOWING_NONE,GWY_TRANSFORM_DIRECTION_FORWARD,GWY_INTERPOLATION_ROUND,TRUE,1) ; gwy_data_field_2dfft_humanize(data_field_fft_r) ; where data_field is obtained from real space data. When displaying the artifical data, it looks pretty good, e.g. like a hexagonal structure. Comparing the coordinates within the differently obtained FFT images, it looks like all the x and y values are way larger in the c-code 2d-FFT (no window) then the one from the gwyddion module. I.e. the very center of the gwyddion-performed fft-image is nearly at (0.002,0.004) nm^-1. But the data reasulting from gwy_data_field_2dfft_humanize(data_field_fft_r) show a center at approx. (3.43886e-08,5.05459e-08)...I guess m^-1. There seems to be a juge difference. Does gwyddion itself calculate the 2d-fft in another way? Thanks for helping. Cheers, /M ------------------------------------------------------------------------------ Want excitement? Manually upgrade your production database. When you want reliability, choose Perforce Perforce version control. Predictably reliable. http://pubads.g.doubleclick.net/gampad/clk?id=157508191&iu=/4140/ostg.clktrk _______________________________________________ Gwyddion-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/gwyddion-users
