eq1 := a(t)*(diff(a(t), t))+a(t)*(diff(a(t), t))*b(t)*(diff(b(t), t))*c(t)*(diff(c(t), t));
eq2 := a(t)*(diff(a(t), t))+a(t)*(diff(a(t), t))*c(t)*(diff(c(t), t))+a(t)*(diff(a(t), t))*b(t)*(diff(b(t), t))*c(t)*(diff(c(t), t));

DEplot({eq1, eq2}, [b(t), c(t)], t = 0 .. 1, b = 0 .. 1, c = 0 .. 1, [[b(0) = 1, c(0) = 1]], arrows = large);

Error, (in DEtools/DEplot/CheckDE) only derivatives of dependent variables can be present

DEplot({eq1 = 3*t^2, eq2 = 2*t^3}, [b(t), c(t)], t = 0 .. 1, b = 0 .. 1, c = 0 .. 1, [[b(0) = 1, c(0) = 1]], arrows = large);
Error, (in DEtools/DEplot/CheckDE) only derivatives of dependent variables can be present

dsolve thousands of system with for loop

but one of system run a very long time, seems never end, just stuck here

how to set timeout when impossible to dsolve

ics:=a(1)=0,b(1)=0,c(1)=0:
ode:=rhs(a4[ii])[1]=1,rhs(a4[ii])[2]=1,rhs(a4[ii])[3]=1:
ode:=a(t)*c(t)*(diff(c(t), t))+2*a(t)*(diff(a(t), t))*b(t) = 1, a(t)*(diff(a(t), t))*b(t)*(diff(b(t), t))*c(t)*(diff(c(t), t))+a(t)*(diff(a(t), t))*b(t)*(diff(b(t), t))+a(t)*(diff(a(t), t)) = 1, a(t)*(diff(a(t), t))*c(t)+2*a(t)*b(t)*(diff(b(t), t)) = 1;
dsol := dsolve({ode,ics}):

for polynomials,

nops(10*x^2)

it return 2, but it is not 1

would like to count some differential equations' terms

for example

b(t)*da(t)/dt + a(t)*b(t) , number of terms is 2

https://drive.google.com/file/d/0Bxs_ao6uuBDUVkE1b2pmcnljcnc/view?usp=sharing
https://drive.google.com/file/d/0Bxs_ao6uuBDUbE56R3Z1c0tLRkE/view?usp=sharing

restart;
changering := proc(Equation1, f3,g3)
g1 := (x,y)-> f3;
f1 := (x,y)-> g3;
h:=subs(g=g1, Equation1);
h:=subs(f=f1, h);
h:=subs(0=0, h);
return h;
end proc:
Eq1 := f(x,g(x,y)) + f(x,y);
h2 := changering(Eq1,x+y, x+y);
h2;

g1 := (x,y)-> x+y;
f1 := (x,y)-> x+y;
h:=subs(g=g1, Eq1);
h:=subs(f=f1, h);
h:=subs(0=0, h);

how to show chain rules result when diff this

Eq1 := f(x,g(x,t)) + f(x,y);
diff(Eq1, x);

 http://math.stackexchange.com/questions/372093/chain-rule-definition-f-fx-gx-y

https://drive.google.com/file/d/0Bxs_ao6uuBDUanVWYm1SMWc4R3M/view?usp=sharing