MagicPlot Manual

Plotting and nonlinear fitting software

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spline [Mon Oct 25 23:13:33 2010]
Alexander
spline [Thu Jan 14 17:12:42 2021] (current)
Alexander
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-====== Using Spline for Baseline Subtraction (Pro edition only) ====== +====== Using Spline for Baseline Subtraction ====== 
-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
  
-Don'use splines to subtract baselines which can be fit well enough with line curve (line or constant baseline). You can subtract wide peaks by mistake 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 =====
-Created spline has anchor points by default. You can move, add and remove anchor points:+Created spline has three anchor points by default. You can move, add and remove anchor points:
  
   * Move anchor point with mouse   * Move anchor point with mouse
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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. 
 + 
 +{{:spline1.png?nolink|Using spline for baseline fitting}}
  
 ===== Fitting with Spline ===== ===== Fitting with Spline =====
  
-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'' check boxes in parameters table+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
  
-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 check ''Set Interval'' check box in the bottom of the panel to edit spline interval, then click on ''Fit One Curve'' button. +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
  
-Set ''Baseline'' check box in spline row in curves table to subtract spline from data.+{{:spline2.png?nolink|Setting Fit Interval for spline curve}} {{:spline3.png?nolink|Spline subtraction result}}
  
-{{:spline2.png|Setting Fit Interval for spline curve}} {{:spline3.png|Spline subtraction result}}+===== See Also =====
  
 +  * [[fitting]]
 +  * [[custom_fit_equation]]
 +  * [[guess_peaks]]
 +  * [[fit_equations]]
spline.1288034013.txt.gz · Last modified: Sun Nov 8 12:20:34 2015 (external edit)