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fft_lowpass_filtering

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T O P I C R E V I E W
couturier	Posted - 04/02/2015 : 05:12:22 AM Origin Ver. and Service Release (Select Help-->About Origin): 2015 Operating System:win7 I have this function for lowpass filtering: int FFT_lowpass(vector& vX, vector& vY, vector & vecOutHPFiltering, double fcutoff) { vecOutHPFiltering = vY; int n = vecOutHPFiltering.GetSize(); double dTimeStep = vX[1] - vX[0]; double dFreq = 1/dTimeStep; double dFreqStep = 1.0/n; double dCutoff = fcutoff/dFreq; fft_lowpass_filtering( n, vecOutHPFiltering, dFreqStep, dCutoff); return 0; } Can anybody explain why it runs well on Origin9 and above but outputs either garbage values (0, *, , , 0, *) or crashes Origin below 9 ? thanks
4 L A T E S T R E P L I E S (Newest First)
couturier	Posted - 04/09/2015 : 09:05:55 AM Thanks for the workaround. For anyone interested by the workaround, first line (//vecOutHPFiltering = vY;) should be uncommented, or the function will not work if output column doesn't already exist.
Shirley_GZ	Posted - 04/09/2015 : 05:02:34 AM Hi Couturier, This is a bug (ORG-5455) which have been fixed since 9.0. You can use the below workaround: int FFT_lowpass(vector& vX, vector& vY, vector & vecOutHPFiltering, double fcutoff) { //vecOutHPFiltering = vY; int n = vecOutHPFiltering.GetSize(); double dTimeStep = vX[1] - vX[0]; double dFreq = 1/dTimeStep; double dFreqStep = 1.0/n; double dCutoff = fcutoff/dFreq; vector v1; v1 = vY; //fft_lowpass_filtering( n, vecOutHPFiltering, dFreqStep, dCutoff); fft_lowpass_filtering( n, v1, dFreqStep, dCutoff); vecOutHPFiltering = v1; return 0; } Thanks, Shirley Originlab Technical Service Team
couturier	Posted - 04/02/2015 : 07:46:36 AM Here are some simple steps: - New a book, fill col(A) with row numbers and col(B) with normal random numbers. - In script window, type the following: range r1=1, r2=2, r3=3; FFT_lowpass(r1, r2, r3, 0.1); I get the following result in col(C): * 0.00% * -1.0033E290 * * -USD 8 686 330 409 166 935 800 000 000 000.00 * 1.91794E-22 * * * * 2.48448E-109 * P€Hc^oß{¼-Øx§ô{°8Naø{ 1.2401335157637E-35 * 1.8E+200% * * -1.3698364388462E-199 * * * JPY 0.559 -0.86485 -1.22789 -2.14137 0.17896 -0.99818 -0.4235 If I run the function a 2nd time, Origin crashes
Shirley_GZ	Posted - 04/02/2015 : 06:03:36 AM Hi Couturier, We have tested your script in both Origin 8.5.1 and 8.6. It works well (Origin doesn’t crash). Would you tell us your detailed steps about how to call this function? If possible would you please send us the sample data via tech@originlab.com? Thanks, Originlab Technical Service Team

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