> # (Anything after `#' is for comments. Maple does not treat them as input.) This is a tutorial to some common commands on solving differential equations.

> with(plots): # Load up the graphic package. End any command with `:' if you don't want to see the output. Otherwise, end it with `;'.

Warning, the name changecoords has been redefined

> with(DEtools): # Load up another package for differential equations.

> ?dsolve;

> # Asking question in the form ``?[subject]'' is a very useful tool to learn new commands and techniques.

> ode:=diff(y(t),t$2)+2*diff(y(t),t)+5*y(t)=cos(t);

ode := diff(y(t), `$`(t, 2))+2*diff(y(t), t)+5*y(t) = cos(t)

> dsolve(ode,y(t));

y(t) = exp(-t)*sin(2*t)*_C2+exp(-t)*cos(2*t)*_C1+1/10*sin(t)+1/5*cos(t)

> ic:=y(0)=10,D(y)(0)=-1;

ic := y(0) = 10, D(y)(0) = -1

> solu:=dsolve({ode,ic},y(t),type=numeric):

> a:=odeplot(solu,[t,y(t)],0..10,color=black):

> display({a});# To plot two or more graphs in one plot, use ``display({a,b})'' with ``b'' any another assigned plot variable similar to ``a'' above. You may use plot package, not necessarily the same as ``odeplot'', to generate ``b''.


> # The following example shows how to solve a system numerically and plot them together against the t-axis.

> sys := {diff(x(t),t)=y(t),diff(y(t),t)=-x(t),x(0)=1,y(0)=2}; # Put the equations and initial conditions together.

sys := {diff(x(t), t) = y(t), diff(y(t), t) = -x(t), x(0) = 1, y(0) = 2}

> syssolu:=dsolve(sys,{x(t),y(t)},type=numeric):

> aa:=odeplot(syssolu,[t,x(t)],0..10,color=black):

> bb:=odeplot(syssolu,[t,y(t)],0..10,color=red):

> display({aa,bb});


> ?dfieldplot; # Find out how to plot direction field.

> DEplot(diff(y(t),t)=y(t)*(1-y(t)),y(t),t=0..10,{[y(0)=0.5],[y(0)=2]}); #Slope field with solutions.


> phaseportrait([D(x)(t)=-x(t)-y(t),D(y)(t)=2*x(t)-y(t)], [x(t),y(t)],t=0..20,[[x(0)=1,y(0)=0],[x(0)=3,y(0)=3]],x=-4..4,y=-4..4,stepsize=.05, scene=[x(t),y(t)],linecolour=sin(t*Pi/2)); # Here is another way to do vector field with solutions.