The QtiPlot Handbook
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# Integrate Function Dialog

This dialog box is opened when you select the Integrate Function... command from the Analysis menu Pressing the Integrate button performs a numerical integration of a user defined analytical function. This function is entered/edited in the Function text box. A combo box which lists internally defined functions is provided. Clicking the "Add" button will copy the selected function into the Function text box at the position of the text cursor. Clicking the "Clear" button will clear the entire contents of the Function text box. Clicking on the "Recent" button opens a dialog which contains a combo box that lists recently used functions. Selecting one of these and clicking "OK" will replace whatever is in the Function text box with the selected function. The second input field displays the name of the independent variable of the function (i.e., the variable of integration). It is set to X by default. The third parameter is the maximum number of subintervals that that the integration algorithm may use to integrate the function. The default value of 1000 should work in almost all circumstances. The fourth parameter is the tolerance limit. Smaller numbers will result in the algorithm using more subintervals. The default value of 0.01 should work for most functions. The next two fields are the lower and upper limits of integration. Set these to whatever values you need. The final item is the Plot Area check box. Leave this checked if you want a plot of the integrated function to be drawn on the currently active layer. A table of the plotted data can be generated by right clicking on the curve and selecting the Worksheet command.

Figure 5-45. The Integrate Function... dialog box.

The numerical result of the integration will be listed in the Log Panel.

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