NPlot is a free charting library for.NET. It boasts an elegant and flexible API. It is particularly well suited to graphing scientific data. It includes Web, Windows.Forms, Bitmap and Gtk# controls. I contributed several examples of NPlot bar charts in VB.NET and C# using the Northwind database and even one using XML as the data source but these examples have not been added to the wiki. I will provide you with enough information here to create bar charts in case someone is still looking for a solution. Difference equation or maps The example is the delayed logistic map x n+1 = a x n-1 (1-x n). This is a second order map and XPP can only solve first order equations. We write it as a pair of first order equations.

nPlot was designed to let science teachers teach science instead of how to wrestle with different graphing programs. For example, uncertainties can simply be entered in the columns labeled '± x' and '± y'. Not all students have the math experience required to linearize their data. With nPlot, they don't have to. The most common mathematical models encountered in introductory physics can be selected with a mouse click.

nPlot now supports up to 3 separate curves. The axes will be scaled so that the data from all three curves fits within the graph. It is not possible to control the scaling of the graph axes. The auto-scaling routine is quite robust. Of course, some students will find ways, through bad data, bad math, or both, to break it. We call these 'teachable moments.'

For now, there is no resorting to scientific notation for graphing large or small data values. Encourage your students to convert their data to micro- or mega-whatevers. To facilitate that, the axis labeling understands Greek. Just type e.g. Delta, delta, or mu to get any letter in the Greek alphabet (that is not already in the Roman one). The labels also understand e.g., ^2 in the usual way.

Fit results and their uncertainties are purposely reported to a ridiculous number of decimal places, so that students have the opportunity to think about uncertainty and precision. (Although the uncertainties in the data grid are drawn on the graph, they do not affect the fit.) Goodness-of-fit is given by the root mean square error (RMSE). Smaller indicates a better fit, but not necessarily a better model. Students will have to be discouraged from choosing a quadratic fit to everything. If the 'Download fit' button is checked, then the numerical results of the fit (or fits) will be downloaded as a separate text file ('fit.txt') when the graph is downloaded (as 'Graph.png'). The student should allow multiple downloads if they get a pop-up asking for permission.

The Tangent Finder does just what it says. When activated, it gives the slope of the fit at the x-value of the mouse position. If a student wants to include a tangent in their downloaded graph, they can slide the mouse off the top edge of the graph at the desired x-value.

Students can prepare their data in Excel or Google Sheets, then copy and paste the whole block into the data grid. Then they can download the completed graph and paste it next to the data table in their spreadsheet and hey! look! an electronic notebook.

Within the data grid, Enter, Tab, and the arrow keys do reasonable things. Shift-delete clears the current cell. If a data cell turns red, it has some problem preventing it from being interpreted as a number. If a data point is suspect, you can check the box in the 'skip' column and it will be ignored. The Clear Data button clears only the currently selected sheet. Holding down the control-key while clicking Clear Data will erase the data from all three sheets.

The Save Sheet feature saves the graph for the currently selected sheet for later Recall, but only on the physical machine the student is using. This is useful only if they have a personal Chromebook or other device. Other aspects of graph saving: holding down the shift key while clicking the Clear Data button will delete all saved graphs. Holding down the shift key while clicking on the name of a saved graph will delete just that graph. In both cases, there is no 'are you sure?' warning. A recalled graph will overwrite whatever is in the currently selected sheet. If the title on a recalled graph is 'undefined', then the student should give it a proper title and re-save it under the original name.

Plot Examples In Romeo And Juliet

The advanced models involve advanced fitting methods. Since this is a program for begining students, some necessary but tricky stuff is done for them. As a result, the majority of the data needs to be in the positive quadrant or the fit will fail (and no curve will be drawn).

Nplot Examples