MATLAB: Is the figure for GAUSSFIR function in the Signal Processing Toolbox documentation the same in R2006a and R2006b, despite the equations used in its implementation being different

Signal Processing Toolbox

I am using the GAUSSFIR function. I notice that the figure for GAUSSFIR function in the Signal Processing Toolbox documentation is the same in R2006a and R2006b, despite the equations in the corresponding MATLAB file being different.

The filter coefficients produced in the two versions are different and so are the figures plotted by 'fvtool'.

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This is an error in the documentation for GAUSSFIR function in the Signal Processing Toolbox 6.6 (R2006b). The documentation should include the figure corresponding to the actual results.

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The answers in both versions are equally good answers. In R12.x and R13 on the PC, the answer is significantly different from that in R11. However, the R12.x and R13 answers on PC are the same as the R11, R12.x and R13 answers on Unix, down to the last bit. This is because the MATLAB computations underlying the BUTTER function uses a different number of bits to store the intermediate values.

Please modify your code as shown below, to obtain the same results for all versions of MATLAB:

samplingrate=500;
lowend=.1;
highend=10;
Wn=[lowend highend]/(samplingrate/2);
% This avoids the piece of code which is generating slightly different
% coefficients between the two versions of MATLAB.
[z,p,k]=butter(8,Wn);
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MATLAB: Does a model containing a Buffer block in an enabled subsystem with Signal Processing Blockset 6.3 (R2006a) produce different results after upgrading to Signal Processing Blockset 6.4 (R2006b)

This is due to a change in the behavior of the Buffer block in enabled subsystems from R2006a to R2006b. Specifically, buffer overflow and under-run protection capability was added to the block in Signal Processing Blockset 6.4 (R2006b). More information about how the Buffer block behaves in an enabled subsystem is available in the documention for the block.

To workaround this issue, inspect your model and rearrange, remove, or add Delay blocks as necessary to recover the expected outcome.

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MATLAB: Does the BUTTER function return different results for Signal Processing Toolbox 4.3 and 5.0

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