Fitting part of a wave in Igor Pro

Most fits are over a window, and there are two ways to say which one.

Function FitTail(WAVE y)
    Variable first = 200, last = numpnts(y) - 1

    Make/O/N=(numpnts(y))/D weights = 1
    weights[0, first - 1] = 0

    CurveFit/Q/M=0 exp_XOffset, y[first, last] /W=weights /I=1 /D

    WAVE W_coef
    Printf "decay constant %.4g\r", W_coef[2]
    return W_coef[2]
End

How it works

1. /R=[first, last] limits the fit to a range of points.
2. A mask wave with /M= excludes points one by one.
3. /W= weights the points, which is how error bars enter a fit.

Keywords and builtins used here

• CurveFit
• End
• Function
• Make
• Printf
• Variable
• WAVE
• numpnts
• return

The run, in numbers

Lines

12

Characters to type

270

Tokens

78

Three-star pace

85 tpm

At the three-star pace of 85 tokens a minute, this run takes about 55 seconds.

Type this snippet

Step 2 of 3 in Curve fitting, step 9 of 16 in Waves & analysis.

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