plot direction field to a system of DEs
dfieldplot(deqns, vars, trange, xrange, yrange, options)
list or set of first order ordinary differential equations
list or set of dependent variables
range of the independent variable
range of the first dependent variable
range of the second dependent variable
(optional) equations of the form keyword=value
Given either a system of two first order autonomous differential equations, or a single first order differential equation, dfieldplot produces a direction field plot. There can be only one independent variable.
For plotting solution curves, see DEplot or phaseportrait.
The direction field presented consists of a grid of arrows tangential to solution curves. For each grid point, the arrow centered at (x,y) will have slope dydx. For system of two first order autonomous differential equations this slope is computed using dydt/dxdt, where these two derivatives are specified in the first argument to dfieldplot. Note: A system is determined to be autonomous when all terms and factors, other than the differential, are free of the independent variable. For more information, see DEtools[autonomous]. For the single first order differential equation, the slope is simply dydx.
Optional equations for dfieldplot are in the DEplot help page.
The xrange and yrange parameters must be specified as follows.
x⁡t=x1..x2, y⁡t=y1..y2 or
By default, integration along a solution curve stops one mesh point after the specified range is exceeded. This may be overridden by the obsrange option.
To execute this section, open this help page as a worksheet and then execute the worksheet.
Example of a single non-autonomous first order differential equation:
Example of a system of two autonomous first order differential equations. This is the command to create the plot from the Plotting Guide.
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