MagicPlot Manual

Plotting and nonlinear fitting software

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spline [Fri Feb 25 14:32:09 2011]
Alexander
spline [Sun Nov 8 12:21:24 2015]
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-====== Using Spline for Baseline Subtraction (Pro edition only) ====== 
-You can use cubic spline to subtract baseline on Fit Plot. To create spline curve click on ''​Add''​ button in ''​Fit Curves''​ tab of Fit Plot and select ''​Spline''​ menu item.  
  
-Do not use splines to subtract baselines which can be fit well enough with ''​Line''​ curve (line or constant baseline). You may mistakenly subtract wide peaks using spline. In some cases ''​Parabola''​ curve may be more suitable. 
- 
-===== Editing Spline ===== 
-Created spline has three anchor points by default. You can move, add and remove anchor points: 
- 
-  * Move anchor point with mouse 
-  * Double click on spline curve to add new anchor point 
-  * Double click on anchor point to remove it 
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-Set ''​Baseline''​ checkbox in spline row in fit curves table to subtract spline from data. 
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-{{:​spline1.png|Using spline for baseline fitting}} 
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-===== Fitting with Spline ===== 
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-Spline anchor point (//x//, //y//) coordinates are treated as fit parameters so you can perform fitting with spline although //we don't recommend this technique//​. Fitting the baseline with some adequate model function is preferred. ​ 
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-It is recommended to set appropriate fit intervals which contain only baseline without peaks. In such case ''​Fit One Curve''​ button is more acceptable than ''​Fit by Sum''​ button, because the individual interval for current curve will be used and the interval from ''​Fit Interval''​ tab (which is used to fit by sum of curves) is ignored. Select spline curve and set ''​Edit Interval''​ checkbox in the bottom of the panel to edit spline interval, then click on ''​Fit One Curve''​ button. The anchor point coordinates will be varied but the number of points will remain. You also can lock some parameters (usually //x// coordinates) by setting ''​Lock''​ checkboxes in parameters table. ​ 
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-{{:​spline2.png|Setting Fit Interval for spline curve}} {{:​spline3.png|Spline subtraction result}} 
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-===== See Also ===== 
- 
-  * [[fitting]] 
-  * [[custom_fit_equation]] 
-  * [[guess_peaks]] 
-  * [[fit_equations]] 
spline.txt ยท Last modified: Sun Nov 8 12:21:24 2015 (external edit)