Hi,

     I have a set of first order, linear ODE's in matrix form, I was able to solve them with matrixDE for 4 equations (which were uncoupled), but I would like to up this to around 132+ equations if possible. When I tried 9 equations I got

 Error, (in collect/series) integer too large in context    

on my laptop and on my other computer it was very slow and I didn't wait for a solution. 

Should I try a numerical solution ...

Say I wanted to print out all values from 1 to 8 but excluding 3, how would I do that using a for loop?

For example, this just stops after 2:

for i to 8 while i <> 3 do
print(i);
end do ;

whereas I want it to skip 3 so going 1,2,4,5,6,7,8.

For what I'm actually doing, I need i to run over a range but excluding one value.

Thanks!

I am not sure if this is a general problem.  And I am considering the best way to evaluate the expression (Equation) when it contains variables which have been modified by using assume.   Here is a tiny test example:

restart;
assume(a>0,x>0);
int(int(x^2/y^2,y=1/x..x),x=1..a);S:=%:  
                        1  4   1   1  2

Greetings to all.

A recent post at math.stackexchange.com asked for good approximations to pi using the nine nonzero digits, the four arithmetic operations and exponentiation. The problem definition definitely suggests a computational solution, which is actually non-trivial because the search space of all legal mathematical expressions over the nine digits and with the aforementioned operations is so huge that it cannot possibly be searched exhaustively.

Hi,

I have the following code which solves a system od ode (3 ode) with constraint parameter. actually, this algorithm is time consuming and is not effective as I see that some people solve this odes with matlab in an efficient (qucik) way. So, I ask you if it is possible help me to improve the efficiency of the following code

thanks

restart:
eq1 := diff(u(eta), eta, eta)+diff(u(eta), eta)/ (eta+zet)+Gr*Pr*T(eta)-Nr*phi(eta)+sigma1;
eq2 := diff(T(eta), eta, eta)+diff(T(eta), eta)/(eta+zet)+Nb*diff(T(eta), eta)*diff(phi(eta), eta)+Nt*diff(T(eta), eta)^2-u(eta);
eq3 := diff(phi(eta), eta,eta)+diff(phi(eta), eta,eta)/(eta+zet)+ Nt/Nb*(diff(T(eta), eta, eta)+diff(T(eta), eta)/(eta+zet))-Le*u(eta);
zet:=0.1:
Nt:=0.05;
Nb:=0.05;
Le:=10;
Pr:=1;
Gr:=5;
Nr:=0.1;
Ree:=5;
#sigma:=2;



p:=proc(pp2) option remember; global res,F0,F1,F2;
if not type([pp2],list(numeric)) then return 'procname(_passed)' end if:
res := dsolve({subs(sigma1=pp2,eq1)=0,eq2=0,eq3=0,u(0)=0,u(1-zet)=0,phi(0)=0,phi(1-zet)=0,T(0)=0,T(1-zet)=0}, numeric,output=listprocedure);
F0,F1,F2:=op(subs(res,[u(eta),phi(eta),T(eta)]));
evalf((2/(1-zet^2))*Int(F0(eta)*(eta+zet),eta=0..1-zet))-Ree*Pr;
end proc;

fsolve(p(pp2)=0,pp2=(-80)..(80));   # I dont know what exactly this parameter has
#res := dsolve({eq1=0,eq2=0,eq3=0,u(0)=0,u(1-zet)=0,phi(0)=0,phi(1-zet)=0,T(0)=0,T(1-zet)=0}, numeric);
 

sigma1:=%;
                             
res := dsolve({eq1=0,eq2=0,eq3=0,u(0)=0,u(1-zet)=0,phi(0)=0,phi(1-zet)=0,T(0)=0,T(1-zet)=0}, numeric);
with(plots):
odeplot(res,[[eta,u(eta)],[eta,phi(eta)],[eta,T(eta)]],0..1-zet);

I have saved array calculated with Digits:=5000. Now I want to save it with Digits:=2500. I tried this

read "C:\\math\\lambda5000.mpl";

Digits := 2500;

LArr2500 := LArr5000;

save LArr2500, "C:\\math\\lambda2500.mpl"

But this don't work...

Hi,

I have a problem solving two equations with trigonometric functions. They are as follows:

eq1:= 9180pi - 16295.070arccos(-1.0 + 0.001356852103xu) + 22.1100sin(-1.0pi + 1.0arccos(-1.0 + 0.001356852103xu))(737.0-xu)+7115.0700arccos(-1.513347022 + 0.002053388090xu) - 14.6100sin(-1.0pi + 1.0arccos(-1.513347022 + 0.002053388090xu))(737.0-xu) + (0.1050As(xu-125)/(1349-xu)) - 0.1050As = 1688

eq2:= 9180pi- 16295.070arccos(-1.0 + 0.001356852103xu) + 22.1100sin...

t0 := arccosh(lambda/(s*(1-lambda)))

f := int(sqrt(lambda-s*cosh(t)/(1+s*cosh(t))), t = -t0 .. t0)

s := 1/10

with(Student[Calculus1])

g := f-Pi*(0+1/2)

Roots(g, lambda = 0 .. 1, numeric)

Why does maple say:

Error, (in mod/Expand) too many levels of recursion?

r(t) = RootOf(Int(_a/sqrt(-4*_a^4+5*_a^2-1), _a = 1 .. _Z)+t), r(t) = RootOf(Int(_a/sqrt(-4*_a^4+5*_a^2-1), _a = _Z .. 1)+t), r(t) = RootOf(Int(_a/sqrt(-4*_a^4+13*_a^2-9), _a = 1 .. _Z)+t), r(t) = RootOf(Int(_a/sqrt(-4*_a^4+13*_a^2-9), _a = _Z .. 1)+t)

ist my result of an ODE

g := dsolve([oder, r(0) = 1, (D(r))(0) = 0])

oder := diff(r(t), t, t) = 4*sqrt(1-(diff(r(t), t))^2)+(1-(diff(r(t), t))^2)/r(t)

Now usually maple gives me one solution, so I can just plot with

Hi all,

This might be more a mathematical problem than a Maple problem, but still maybe somebody could help me out.

I am trying to solve the differential equation of an Euler-Bernoulli beam with an distributed load (q1) and a varying axial force (N(x)). The following equation applies:

I have a rather large number of combinations to search and would like to use Task in order to take advantage of my multicore machine. The easiest way it seems to me to use Task to break up the total number of combinations into say, four pieces. Any one familiar with Task have any suggestions?

Hello Folks:

I'm trying to generate a plot of a procedure that uses fsolve and I get the following error message:

> implicitplot(IC(2, x, y, 1, 1), .1 .. .9, -1 .. 1, filled = true, numpoints = 10);
Error, (in fsolve) x is in the equation, and is not solved for

It seems that Maple is passing x to the procedure IC and not the numerical value of x.

I tried, without success,  to delay the evaluation as suggested here

I have some automatically generated maple code. The code is in fact entirely within a single MAPLE object module. The auto generated code is ugly; fixing it is not feasible. Dealing with it by hand is not feasible.

If you have an ugly MAPLE proc, and just want to get a standard format for the code in the proc, you can print the proc in a maple command window and copy-past it back into the source file. *poof* it looks better. You loose the comments but who needs those anyway :...

Hi,

I'm trying to generate all the possible combinations of each M[i] according to the possible values for c,d and e. The code I have here generates some of them but not all - it misses out the combinations when the two or three elements in the square brackets are different ie. 

it generates
[{1}, [{1}, {1}], [{1}, {1}, {1}]]               
[{1}, [{2}, {2}], [{2}, {2}, {2}]]             

Hello guys,
I'm newb with Maple and trying to solve the following nonlinear recurrence system:

rsolve ({L(0)=1,L(n)=1.025*L(n-1),h(n)=L(n)/(1.1*L(n)-0.1*v(n-1)),v(0)=0.5,v(n)=(1+h(n))*v(n-1)},{L,h,v});

But Maple returns me nothing, no error. What's might be the problem?

Thanks in advance.