[Octave-bug-tracker] [bug #39562] Package signal, function fwht, parameter "dyadic" produces wrong result

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?39562>

                 Summary: Package signal, function  fwht, parameter "dyadic"
produces wrong result
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Wed 24 Jul 2013 06:13:48 PM UTC
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Alex
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.6.4
        Operating System: GNU/Linux

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Details:

The title says everything - Octave produces a result that does not match
Matlab or literature values.

Package: signal
Function: fwht, third parameter = "dyadic"

Here is a basic functioning code that exemplifies the problem:

N=1024; t = linspace(-5,5, N);
f=t.**100;

pkg load signal
F =  fwht(f,N,"dyadic"); #<--- "sequency" or "hadamard" 
                         #      produces correct results
Finv = ifwht(F,N,"dyadic");

#Normalization for visualization:
out1=t;
out2=abs(F)/norm(F);
out3=abs(Finv)/norm(Finv);
out4=f/norm(f);

plot(t,out4) #original function
hold on;
plot(t,out3) #plot reconstruction: notice that right hand sideof 
             #original function is reconstructed completely wrong
hold off;

The same code in Matlab produces a correct result (correct reconstruction,
matches literature).





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