MaplePrimes - answers and comments on Question, do-loop for ODe

Move the end do;

dskoog — Wed, 25 Jan 2012 01:30:24 Z

Perhaps you meant to have the end do; at the end of your code:

restart;
with(DEtools): with(plots):
lambda := 0.1; delta := .5;
tau := 40;
for k to 3 do 365*k;
ode := diff(U(t), t) = -lambda(t)*U(t)*U(t);
inc1 := U(0) = 100;
sol1 := dsolve({inc1, ode}, U(t), numeric);
F := proc (t) options operator, arrow; rhs(sol1(t)[2]) end proc;
F(365*k+tau+0);
Z := (1-delta)*F(365*k+tau+0);
inc2 := U(365*k+tau+0) = Z;
sol2 := dsolve({inc2, ode}, U(t), numeric);
end do;

which returns U(405), U(770), U(1135).

Hello, Thank you for yor replay. I received

reemeaaaah — Wed, 25 Jan 2012 02:17:39 Z

Hello,

Thank you for yor replay. I  received an error when I run it. for k to 3 until end do

is in one maple input right?

Thanks

> restart;
> with(DEtools); with(plots);
> lambda := 0.1; delta := .5; tau := 40;
> for k to 3 do 365*k;

 ode:=diff(U(t),t)=-(lambda(t)U(t))U(t);

inc1 := U(0) = 100;   ;

sol1 := dsolve({inc1, ode}, U(t), numeric);

F := proc (t) options operator, arrow; rhs(sol1(t)[2]) end proc;

F(365*k+tau+0);
Z:=(1-delta[])*F((365 k)+tau[]+0);

inc2:=U((365 k)+tau[]+0)= Z;

 sol2:=dsolve({ode,inc2},U(t),numeric);

end do; ;
Error, (in dsolve/numeric/process_input) system must be entered as a set/list of expressions/equations
t -> rhs(sol1(t)[2])
Error, (in F) invalid input: rhs received sol1(365*k+40)[2], which is not valid for its 1st argument, expr
>

Running the code works

dskoog — Wed, 25 Jan 2012 02:43:12 Z

Running the code that I suggested works fine in Maple 13 through 15. However, your modified code does not. Perhaps you need to examine the parts that you modified (such as the tau & delta terms which now have the additional [] ).

@dskoog I have maple 14. I copied

reemeaaaah — Wed, 25 Jan 2012 05:50:38 Z

@dskoog

I have maple 14. I copied your code and run it. It works with no errors. Thanks you so much for your help