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FFTSmooth v1

../_images/ImageNotFound.png

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Warning

FFTSmooth is deprecated. Use FFTSmooth version 2 instead.

Summary

Performs smoothing of a spectrum using various filters.

Properties

Name

Direction

Type

Default

Description

InputWorkspace

Input

MatrixWorkspace

Mandatory

The name of the input workspace.

OutputWorkspace

Output

MatrixWorkspace

Mandatory

The name of the output workspace.

WorkspaceIndex

Input

number

0

Workspace index for smoothing

Filter

Input

string

Zeroing

The type of the applied filter. Allowed values: [‘Zeroing’]

Params

Input

string

The filter parameters

Description

FFTSmooth uses the FFT algorithm to create a Fourier transform of a spectrum, applies a filter to it and transforms it back. The filters remove higher frequencies from the spectrum which reduces the noise.

This version of the FFTSmooth algorithm has one filter:

Zeroing

  • Filter: “Zeroing”

  • Params: “n” - an integer greater than 1 meaning that the Fourier coefficients with frequencies outside the 1/n of the original range will be set to zero.

Usage

Example: Zeroing with Params=2

ws = CreateSampleWorkspace(function="Multiple Peaks",XMax=20,BinWidth=0.2,BankPixelWidth=1,NumBanks=1)

#add a bit of predictable noise
noiseAmp=0.1
noiseArray= []
for i in range(ws.blocksize()):
    noiseAmp = -noiseAmp
    noiseArray.append(noiseAmp)

for j in range(ws.getNumberHistograms()):
    ws.setY(j,ws.readY(j)+noiseArray)


wsSmooth = FFTSmooth(ws, Params='2', Version=1)

print("bin Orig  Smoothed")
for i in range (0,100,10):
    print("{}  {:.2f}  {:.2f}".format(i, ws.readY(0)[i], wsSmooth.readY(0)[i]))
../_images/FFTSmoothZeroing.png

Output:

bin Orig  Smoothed
0  0.20  0.30
10  0.20  0.30
20  0.37  0.47
30  10.20  10.30
40  0.37  0.47
50  0.20  0.30
60  8.20  8.30
70  0.20  0.30
80  0.20  0.30
90  0.20  0.30

Categories: AlgorithmIndex | Arithmetic\FFT | Transforms\Smoothing | Deprecated

Source

C++ header: FFTSmooth.h

C++ source: FFTSmooth.cpp