Online Algebra Calculator
Many of users do not use powerful Maxima computer algebra system for systematic work, but for ad hoc algebraic calculations – equations, functions, matrixes, etc. only. To do this job, it is not useful to download the whole application from a web site.
Function: desolve (<eqn>, <x>)

Function: desolve ([<eqn_1>, ..., <eqn_n>], [<x_1>, ..., <x_n>]) The function desolve solves systems of linear ordinary differential equations using Laplace transform. Here the <eqn>s are differential equations in the dependent variables <x_1>, ..., <x_n>. The functional dependence of <x_1>, ..., <x_n> on an independent variable, for instance <x>, must be explicitly indicated in the variables and its derivatives. For example, this would not be the correct way to define two equations:
eqn_1: diff(f,x,2) = sin(x) + diff(g,x); eqn_2: diff(f,x) + x^2 - f = 2*diff(g,x,2);
The correct way would be:
eqn_1: diff(f(x),x,2) = sin(x) + diff(g(x),x); eqn_2: diff(f(x),x) + x^2 - f(x) = 2*diff(g(x),x,2);
The call to the function desolve would then be desolve([eqn_1, eqn_2], [f(x),g(x)]);
If initial conditions at x=0 are known, they can be supplied before calling desolve by using atvalue.
(%i1) diff(f(x),x)=diff(g(x),x)+sin(x);
d d
(%o1) -- (f(x)) = -- (g(x)) + sin(x)
dx dx
(%i2) diff(g(x),x,2)=diff(f(x),x)-cos(x);
2
d d
(%o2) --- (g(x)) = -- (f(x)) - cos(x)
2 dx
dx
(%i3) atvalue(diff(g(x),x),x=0,a);
(%o3) a
(%i4) atvalue(f(x),x=0,1);
(%o4) 1
(%i5) desolve([%o1,%o2],[f(x),g(x)]);
x
(%o5) [f(x) = a %e - a + 1, g(x) =x cos(x) + a %e - a + g(0) - 1]
(%i6) [%o1,%o2],%o5,diff;
x x x x
(%o6) [a %e = a %e , a %e - cos(x) = a %e - cos(x)]
If desolve cannot obtain a solution, it returns false.
(%o1) true (%i2)