![]() | Analysis |
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With the analysis dialogs you can analyse a graph with different methods. By applying a method you create a new graph which is inserted in the active plot.
Most of the analysis functions can also be applied to a spreadsheet. From the selected columns of the spreadsheet a new column with the resulting values is created.
If you have at least two graphs in the active plot you can operate on this data set in this dialog. You can add, substract, multiply and divide daat sets here.
With this dialog you can average over n points of a graph. The number of points is so reduced by a factor of 1/n.
This dialog does the same as average but for every data point. So you will get a smoothed graph with equal number of data points.
This dialog reduces the number of data points by just using every n-th point. The resulting number of points is so reduced by a factor of 1/n.
With this dialog you can make a histogram of a graph. That means that the y-range is seperated in n bins and every datapoint fitting in one bin is counted. You will get a graph which shows the number per bin vs. the bin number. The used y-range and number of bins can be selected in this dialog.
Interpolations tries to find a smooth curves through a given set of data points. You can use different types of interpolation to do that : linear, polynomial, cspline, akima. All datapoints in the active region are used for interpolation, but any x-range and number of points for the interpolating function may be selected as well.
This dialog can be used to numerical integrate a graph. You can specify to only use a certain region. Additionaly you can sum the absolute values to calculate the area under a graph. The baseline for integration can also be specified.
With the "Add Graph" checkbox you can select whether to add the integrated graph. With the "Show Info" checkbox selected the cummulative sum is shown in a seperate window.
The regression dialog can be used to fit a graph with polynomials up to the 10-th order. The weigth and model can be specified.
The number of points and the range of the fitted function can be user defined.
With this dialog you can calculate the fourier transform of a graph. LabPlot can use the fftw or gsl library for that. You can select whether to transform froward or backward. The x-values can be use as index, frequency or period. The y-values are calculated as magnitude, phase, real or imaginary part.
With this dialog you can calculate the convolution of one graph with another. LabPlot uses the FFT of gsl for that. It is also possible to deconvolve a set. The x-values can be use as index or same as the signal set.
With the nonlinear fit dialog you can fit a graph with functions outside of the simple regression scope. You can select one of 12 different models . The initial values can be selected too. Please note that fitting especially the exponential models is very sensitive to the initial values.
If specified, only the datapoints in the region are used. You can also specify the baseline of the fit function. The range and the number of points for the fit function can be selected too.
The resulting fit parameter are shown in the bottom field and automatically replaced as initial values for further fitting.
In this dialog you can manipulate the matrix or image data of the active plot (for instance surface plot).
LabPlot uses the API of ImageMagick to convert the image with about 50 different methods. You can select the size of the resulting image with the "height" and "width" line edits.
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