SolveODE Command
From GeoGebra Manual
Revision as of 13:04, 25 August 2011 by Alexander Hartl (talk | contribs)
- SolveODE[ <f'(x,y)>, <Start x>, <Start y>, <End x>, <Step> ]
- Solves first order ordinary differential equations (ODE) \frac{dy}{dx}=f'(x,y) numerically given start point and end & step for x.
- For example to solve \frac{dy}{dx}=-xy using A as a starting point, enter SolveOde[-x*y, x(A), y(A), 5, 0.1]
- SolveODE[ <f(x,y)>, <g(x,y)>, <Start x>, <Start y>, <End t>, <Step> ]
- Solves first order ODE \frac{dy}{dx}=\frac{f(x,y)}{g(x,y)} given start point, maximal value of an internal parameter t and step for t. This version of the command may work where the first one fails eg when the solution curve has vertical points.
- For example, to solve \frac{dy}{dx}=- \frac{x}{y} using A as a starting point, enter SolveOde[-x, y, x(A), y(A), 5, 0.1].
- SolveODE[ <b(x)>, <c(x)>, <f(x)>, <Start x>, <Start y>, <Start y'>, <End x>, <Step>]
- Solves second order ODE y''+b(x)y'+c(x)y=f(x).
- Note: Always returns the result as locus. The algorithms are based on Runge-Kutta numeric methods.
CAS Syntax
Following two syntaxes work only in CAS View.
- SolveODE[ <f(x, y)> ]
- Attempts to find the exact solution of the first order ODE \frac{dy}{dx}(x)=f(x, y(x)).
- Example:
SolveODE[y / x]
yields y = c1 x.
- SolveODE[ <f(v, w)>, <Dependend Variable v>, <Independend Variable w> ]
- Attempts to find the exact solution of the first order ODE \frac{dv}{dw}(w)=f(w, v(w)).
- Example:
SolveODE[y / x, y, x]
yields y = c1 x.