First of all. thank you for your fast response.
I tried this:
x:make_array(flonum,64);
y:make_array(flonum,64);
for i:0 thru 63 do x[i]:float(random(1000));
for i:0 thru 63 do y[i]:float(random(1000));
b:fft(x,y);
but i take this for b:
fft(Lisp array [64],Lisp array [64])
How can i see the values of b;
Thanks again,
Nick
???? 6 ????????? 2008 3:23 ??, ? ??????? Alasdair McAndrew <amca01 at gmail.com
> ??????:
> Well, for a start, fft requires two arrays, each of which must be of length
> a power of 2. So here's one way:
>
> x:make_array(flonum,64);
> y:make_array(flonum,64);
> for i:0 thru 63 do x[i]:float(random(1000));
> for i:0 thru 63 do y[i]:float(random(1000));
> fft(x,y);
>
> Since the operations are performed in place, the arrays x and y now contain
> the real and imaginary parts of the transform.
>
> ift(x,y);
>
> And now the arrays x and y contain the real and imaginary parts of the
> original data (with some rounding errors). I don't think this sort of
> operation is Maxima's strength - if you want a free Matlab-like package
> which includes ffts you should investigate Scilab.
>
> -Alasdair
>
> On Mon, Oct 6, 2008 at 9:40 PM, ????? ??????? <mparmpaklo at gmail.com>wrote:
>
>> Hello,
>>
>> i am a postgraduate student in Applied Informatics and i am using maxima
>> about a month.
>>
>> I have problem using some functions of maxima and i will need your help.
>>
>> The functions that i cannot understand are these: fft, ifft, dgesvd and
>> gamma.
>>
>> 1) fft
>>
>> I would like to do compute this:
>>
>>
>> x: makelist(i*random(1000),i,1,100);
>> b:fft(x);
>>
>> but i get an error.
>>
>> I used to perform this operation in matlab like this, but i can't figure
>> out how this function works.
>>
>>
>> 2) ifft
>>
>> I would like to do compute this:
>>
>>
>> x: makelist(i*random(1000),i,1,100);
>> b:ift(x);
>>
>> but i get an error.
>>
>>
>> 3) dgesvd
>>
>> h [i, j] := (1 + i*random(1000) + j)/(j*random(1000))+random(1000);
>> x: genmatrix(h,10,10);
>> b: dgesvd(x);
>>
>> but again i get an error.
>>
>>
>>
>> 4) gamma
>>
>> h [i, j] := (1 + i*random(1000) + j)/(j*random(1000))+random(1000);
>> x: genmatrix(h,10,10);
>> b: gamma(x);
>>
>> but again i get an error.
>>
>>
>>
>>
>> I use Maxima 5-16.3 under Windows.
>>
>>
>> Thank you anyway,
>> Nick
>>
>> _______________________________________________
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>> Maxima at math.utexas.edu
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>>
>>
>
>
> --
> Blog: http://amca01.wordpress.com
>