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  • Guest's Avatar
    Guest replied
    Here's FFT source code:

    Code:
    DECLARE FUNCTION bitRev&(j&,nu&)
    
    FUNCTION bitRev&(j&,nu&)
        j1&=j&
        k&=0
        FOR i&=1 TO nu&
            j2&=j1&\2
            k&=k&*2+j1&-2*j2&
            j1&=j2&
        NEXT i&
        FUNCTION=k&
    END FUNCTION
    
    SUB newFFT(ftr AS DOUBLE PTR, fti AS DOUBLE PTR, jmax&,nu&)
        n2&=jmax&\2
        nu1&=nu&-1
        k&=0
        dw#=2*pi#/jmax&
        FOR l&=1 TO nu&
            pt&=1
            SHIFT LEFT pt&,nu1&
            DO WHILE k&<jmax&
                FOR i&=1 TO n2&
                    p#=bitRev(k&\pt&,nu&)
                    arg#=p#*dw#
                    c#=COS(arg#)
                    s#=SIN(arg#)
                    trl#[email protected][k&+n2&]*c#[email protected][k&+n2&]*s#
                    tim#[email protected][k&+n2&]*c#[email protected][k&+n2&]*s#
                    @ftr[k&+n2&][email protected][k&]-trl#
                    @fti[k&+n2&][email protected][k&]-tim#
                    @ftr[k&][email protected][k&]+trl#
                    @fti[k&][email protected][k&]+tim#
                    INCR k&
                NEXT i&
                k&=k&+n2&
            LOOP
            k&=0
            nu1&=nu1&-1
            n2&=n2&\2
        NEXT l&
        k&=0
        DO WHILE k&<jmax&
            i&=bitRev&(k&,nu&)
            IF i&>k& THEN
                trl#[email protected][k&]
                tim#[email protected][k&]
                @ftr[k&][email protected][i&]
                @fti[k&][email protected][i&]
                @ftr[i&]=trl#
                @fti[i&]=tim#
            END IF
            INCR k&
        LOOP
    END SUB
    The code executes in realtime in PBCC10 (SB Input, double-buffered)
    Converted from Pascal (original program / source PSK31 by Peter Martinez, I think)




    -------------
    Daniel
    [email protected]

    Leave a comment:


  • E Dingsor
    replied
    Peter,
    Go to http://www.ulib.org/webRoot/Books/Numerical_Recipes/

    There You'll find Fortran or C++ code. It's easy to translate to Basic. They used to have Neumerical Recipes for Basic, but I'm not sure if it still in stock.
    Anyway, Numerical REcipes is a need to have book if You do a lot of math programming.

    Best regards

    Eigil

    Leave a comment:


  • Guest's Avatar
    Guest started a topic Solver, Inverting, FFT ect...

    Solver, Inverting, FFT ect...

    Has anybody seen PowerBasic-algoritms for:

    1) solving non-linear systems
    2) solving (large) linear systems
    3) FFT

    Regards
    Peter
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