Fast Fourier transform: Difference between revisions
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1¼ cycle wave: .000⊥.000, .000⊥.001, .000⊥.000, .000⊥-8.001, .000⊥.000, -.000⊥-.001, .000⊥.000, .000⊥.001, .000⊥.000, .000⊥-.001, .000⊥.000, -.000⊥.001, .000⊥.000, -.000⊥8.001, .000⊥.000, -.000⊥-.001, |
1¼ cycle wave: .000⊥.000, .000⊥.001, .000⊥.000, .000⊥-8.001, .000⊥.000, -.000⊥-.001, .000⊥.000, .000⊥.001, .000⊥.000, .000⊥-.001, .000⊥.000, -.000⊥.001, .000⊥.000, -.000⊥8.001, .000⊥.000, -.000⊥-.001, |
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</pre> |
</pre> |
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=={{header|BBC BASIC}}== |
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{{works with|BBC BASIC for Windows}} |
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<lang bbcbasic> @% = &60A |
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DIM Complex{r#, i#} |
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DIM in{(7)} = Complex{}, out{(7)} = Complex{} |
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DATA 1, 1, 1, 1, 0, 0, 0, 0 |
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PRINT "Input (real, imag):" |
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FOR I% = 0 TO 7 |
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READ in{(I%)}.r# |
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PRINT in{(I%)}.r# "," in{(I%)}.i# |
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NEXT |
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PROCfft(out{()}, in{()}, 0, 1, DIM(in{()},1)+1) |
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PRINT "Output (real, imag):" |
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FOR I% = 0 TO 7 |
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PRINT out{(I%)}.r# "," out{(I%)}.i# |
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NEXT |
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END |
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DEF PROCfft(b{()}, o{()}, B%, S%, N%) |
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LOCAL I%, t{} : DIM t{} = Complex{} |
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IF S% < N% THEN |
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PROCfft(o{()}, b{()}, B%, S%*2, N%) |
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PROCfft(o{()}, b{()}, B%+S%, S%*2, N%) |
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FOR I% = 0 TO N%-1 STEP 2*S% |
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t.r# = COS(-PI*I%/N%) |
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t.i# = SIN(-PI*I%/N%) |
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PROCcmul(t{}, o{(B%+I%+S%)}) |
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b{(B%+I% DIV 2)}.r# = o{(B%+I%)}.r# + t.r# |
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b{(B%+I% DIV 2)}.i# = o{(B%+I%)}.i# + t.i# |
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b{(B%+(I%+N%) DIV 2)}.r# = o{(B%+I%)}.r# - t.r# |
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b{(B%+(I%+N%) DIV 2)}.i# = o{(B%+I%)}.i# - t.i# |
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NEXT |
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ENDIF |
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ENDPROC |
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DEF PROCcmul(c{},d{}) |
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LOCAL r#, i# |
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r# = c.r#*d.r# - c.i#*d.i# |
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i# = c.r#*d.i# + c.i#*d.r# |
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c.r# = r# |
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c.i# = i# |
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ENDPROC |
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</lang> |
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Output: |
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<pre>Input (real, imag): |
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1, 0 |
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1, 0 |
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1, 0 |
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1, 0 |
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0, 0 |
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0, 0 |
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0, 0 |
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0, 0 |
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Output (real, imag): |
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4, 0 |
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1, -2.41421 |
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0, 0 |
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1, -0.414214 |
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0, 0 |
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1, 0.414214 |
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0, 0 |
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1, 2.41421</pre> |
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=={{header|C}}== |
=={{header|C}}== |
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