MagicPlot Manual

Plotting and nonlinear fitting software

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spline [Sun Oct 31 21:13:46 2010]
Gray
spline [Mon Jun 3 16:47:16 2013]
Alexander
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 ====== Using Spline for Baseline Subtraction (Pro edition only) ====== ====== Using Spline for Baseline Subtraction (Pro edition only) ======
-You can use cubic spline to fit and subtract baseline on Fit Plot. To create spline curve click on ''Add'' button in ''Fit Curves'' tab of Fit Plot. +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.+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 ===== ===== Editing Spline =====
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   * Double click on anchor point to remove it   * Double click on anchor point to remove it
  
-{{:spline1.png|Using spline for baseline fitting}}+Set ''Baseline'' checkbox in spline row in fit curves table to subtract spline from data.
  
-===== Fitting with Spline =====+{{:spline1.png?nolink|Using spline for baseline fitting}}
  
-Spline anchor point (//x//, //y//) coordinates are treated as fit parameters so you can perform fitting with spline. Note that the anchor point coordinates will be varied but the number of point will remain. You also can lock some parameters (usually //x// coordinates) by setting ''Lock'' checkboxes in parameters table. +===== Fitting with Spline =====
  
-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'' buttonbecause 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 ''Set Interval'' checkbox in the bottom of the panel to edit spline interval, then click on ''Fit One Curve'' button+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
  
-Set ''Baseline'' checkbox in spline row in curves table to subtract spline from data.+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. 
  
-{{:spline2.png|Setting Fit Interval for spline curve}} {{:spline3.png|Spline subtraction result}}+{{:spline2.png?nolink|Setting Fit Interval for spline curve}} {{:spline3.png?nolink|Spline subtraction result}}
  
 ===== See Also ===== ===== See Also =====
spline.txt ยท Last modified: Thu Jan 14 17:12:42 2021 by Alexander