Since I am a very recent Maple user, I do not know why I obtained a wrong answer with the following two comands:

Exp:= Psi(rho(x,t),theta(x,t));
                  Psi(rho(x, t), theta(x, t))
Exp1:= diff(Exp,t);
     / d           \                                  
     |--- rho(x, t)| D[1](Psi)(rho(x, t), theta(x, t))
     \ dt          /                                  

          / d             \                                
    + |--- theta(x, t)| Psi(rho(x, t) + 1, theta(x, t))
          \ dt            /                                
 

Can someone, please, help me?

Thank you.

I am using Maple to model Gaussian Wave Packets and the do loop creates an array of plots. I want to animate these plots to show the movement of the wave packet and was wondering if there is a way to animate the array or perhaps another way to produce the animation. 

Hi,

I have a function "L" which is mentioned in the worksheet. I want to obtain equation of motion by solving Euler-Lagrange equation. How I can do this by maple? Have Maple an instruction to solve Euler-Lagrange equation?        ELEOM.mw

how to add two algebaric equations? I have two equation (1) and (2). i simply wrote (1) + (2) instead of adding the eqautions i got result is 3. i think there is some mistake of writng text for calling equation that was in bold. 

adding_two_equations.mw

I am trying to evaluate the following triple integral but it takes much time so i kill the job.

Download int_maple_prime2.mw

Maple newbie here.

I do not understand why algsubs do not replace the symbol in the denominator in the following example, but does replace it in the numerator. This is on Maple 2017 on windows 7

Here is the expression

sol := u(x, t) = Sum((2*cos((1/2)*Pi*_Z1)+
       2+4*(-1)^(1+_Z1))*sin(Pi*_Z1*x/L)*
       exp(-k*Pi^2*_Z1^2*t/L^2)/(Pi*_Z1), 
       _Z1 = 1 .. infinity);

I wanted to replace _Z1  with n

But algsubs will not replace _Z1 in the denominator as seen in this screen shot but subs does:

From help, my impression is that algsubs is superset of subs. Only case where algsubs will not do what subs does is, according to help:

But There is no indexed names here? 

Can someone please explain why algsubs fails to do the substitution in the denominator in this example?

I am trying to evaluate the following function for which I am getting a result 0. I just need to make sure the approach as well as result is correct or not. Thanks in advance. 
 

Download int(maple_prime).mw

I did change of variables as below:

Download simplifyss.mw

But I amezed when I use simplify command deteriorate my eq.

Why?

UPDATE

Thanks for checking. I verify I get the error and made screen shots below

When I add the convert() command, the error goes away. Here is screen shot

I am using Maple 2017, student version, on windows 7, 64 bit, home edition.

Original post

This is using Maple 2017 on windows.

With the following input, Maple pdsolve gives an error

pde:=diff(u(x,t),t)=k*diff(u(x,t),x$2);
bc:=D[1](u)(0,t)=0,D[1](u)(L,t)=0:
assume(L>0):
ic:=u(x,0)=piecewise(0<x and x<=L/2,0,L/2<x and x<L,1):
sol:=pdsolve([pde,bc,ic],u(x,t)):

However, if I add one line to convert the piecewise function above to piecewise, then pdsolve no longer gives an error. So the following input works

restart;
pde:=diff(u(x,t),t)=k*diff(u(x,t),x$2);
bc:=D[1](u)(0,t)=0,D[1](u)(L,t)=0:
assume(L>0):
ic:=u(x,0)=piecewise(0<x and x<=L/2,0,L/2<x and x<L,1):
ic:=convert(ic,piecewise,x):
sol:=pdsolve([pde,bc,ic],u(x,t)):

Notice the extra line. Why does one have to convert piecewise to piecewise to make pdsolve accept the input?

sorry did not write down the error message and I am writing this from school library PC. But if you try the first case, you'll see the error.

Hi! I have the system of differential equations

restart; with(plots); with(DEtools);

a := 1;

deq1 := u(s)*(diff(varphi(s), s, s))+2*(diff(u(s), s))*(diff(varphi(s), s))+sin(varphi(s)) = 0;

deq2 := diff(u(s), s, s)-u(s)*(diff(varphi(s), s))^2-cos(varphi(s))+a*(u(s)-1) = 0;

sol := dsolve({deq1, deq2, u(0) = 1, varphi(0) = (1/4)*Pi, (D(u))(0) = 0, (D(varphi))(0) = 0}, {u(s), varphi(s)}, numeric)

which is perfectly solved, but I need to convert it to Cartesian coordinates and draw a plot, so what I tried is

x := u(s)*sin(varphi(s));

y := -u(s)*cos(varphi(s));

plot([x, y, s = 0 .. 20])

But I'm getting an error "Warning, expecting only range variable s in expressions [u(s)*sin(varphi(s)), -u(s)*cos(varphi(s))] to be plotted but found names [u, varphi]"

I don't know why is this happens if I have a solution. For example, I can get solution for 2 seconds:

sol(2)

[s = 2., u(s) = 2.33095721668252, diff(u(s), s) = 1.02513293353371, varphi(s) = .213677391510693, diff(varphi(s), s) = -.242430995691885]

I posted my question at here https://math.stackexchange.com/questions/2314488/how-can-i-find-maximum-and-minimum-modulus-of-a-complex-number.
With Mathematica, I got min is 22/5. This result is different from my solution by hand.

Repeat my problem. Let be the number z so that $|z+1| + 4|z-1| = 25$. Find the greastest and the least of the modulus of $z$. How can I find greastest and the least of modulus of z with Maple.

How can we find ricci tensor of a metric attaced in given file that involve two unknown functions phi(r) and nu(r).metric.mw

i have an optimization problem, i want to maximize an expression using assumption, what should i do?

Download optimize.mw

I have final project to make a media for learning mathematic using maple. But I'm so confused to make a net of cuboid, anybody can help me? please :D