Discrete Fourier transform calculator

Calculate real transform components and imaginary transform components with your own figures.

Your numbers

Use the units shown. Results update as you change valid inputs.

Use real transform components and imaginary transform components to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Real sample components
1,0,0,0
Imaginary sample components
0,0,0,0
Direction: forward or inverse
forward
Normalization: backward, forward or ortho
backward
Real transform components
1, 1, 1, 1
Imaginary transform components
0, 0, 0, 0
Two-sided bin magnitudes
1, 1, 1, 1
Bin phases (degrees; zero at numerical zero magnitude)
0, 0, 0, 0

Try another scenario

Real sample components
1,1,1,1
Imaginary sample components
0,0,0,0
Direction: forward or inverse
forward
Normalization: backward, forward or ortho
backward
Real transform components
4, 0, 0, 0
Imaginary transform components
0, 0, 0, 0
Two-sided bin magnitudes
4, 0, 0, 0
Bin phases (degrees; zero at numerical zero magnitude)
0, 0, 0, 0
Calculation method

Calculation method

Real transform components

Sum samples against exp(−2πikj/N) for forward or exp(+2πikj/N) for inverse, retaining the real components.

Imaginary transform components

Imaginary components of the same transform.

Two-sided bin magnitudes

sqrt(real²+imag²) per bin; this is not a one-sided amplitude spectrum.

Bin phases (degrees; zero at numerical zero magnitude)

atan2(imaginary,real) in degrees; roundoff-scale components are set to zero before phase evaluation. Backward scales inverse by 1/N, forward scales forward by 1/N, ortho scales both by 1/sqrt(N).

Symbols and units
a
Real sample components
b
Imaginary sample components
c
Direction: forward or inverse
d
Normalization: backward, forward or ortho

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Assumptions & limits

Assumptions & limits

  • Direct O(N²) real/complex DFT for at most 128 matched samples. No sample rate, windowing, frequency labels or one-sided power correction is inferred. Double-precision results are approximate. Numeric tables use 12 significant digits and display components at roundoff scale (32 machine epsilons relative to their row or relevant calculation scale) as zero; scalar diagnostics retain full precision.
Are these inputs private?

These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.

Further reading

NumPy: DFT normalization and transform conventions ↗

Background reading; this does not imply endorsement or independent review of SumFizz.

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