javid basha jv

6 years, 53 days

## "unable to compute solution for t>HFloat...

Maple 18

Hi maple users

I am working with the PDE solver.

i am receiving a following error

"unable to compute solution for t>HFloat(0.0):"

Kindly do the needful how to rectify this error.

dumm.mw

## How to rectify the "Error, invalid subsc...

Maple 18

Hi, Maple users

I hope you are doing well.
Here I solved one of the ode problems by dsolve.
But I am getting  "Error, invalid subscript selector" error.
Kindly do the needful to find a solution.
Thank you.

JVB.mw

## How to integrate the indefinite integral...

Maple 18

Dear maple users,

A fine day wishes to all.

I have solved the PDE via PDsolve. Here I need to calculate the Psi function. How to calculate the indefinite integral and how to find the constant-coefficient (C1).

Here Psi=0 at x=0

int_c.mw

 > restart:
 > with(PDEtools):
 > with(plots):
 > fcns := {f(x,t),theta(x,t)};
 (1)
 > d:=0.5:xi:=0.1:
 > R:=z->piecewise(d<=z and z<=d+1,1-2*xi*(cos((2*3.14)*((z-d)*(1/2))-1/4)-(7/100)*cos((32*3.14)*(z-d-1/2))),1);
 (2)
 > PDE1 :=(diff(f(x,t),t))=1+(1-2*theta((x,t)))*(1/(R(z)^2))*((diff(f(x,t),x,x))+(1/x)*diff(f(x,t),x))+theta((x,t));
 (3)
 > PDE2 :=2*(diff(theta(x,t),t))=(1/(R(z)^2))*((diff(theta(x,t),x,x))+(1/x)*diff(theta(x,t),x));
 (4)
 > IBC := {D[1](f)(0,t)=0,f(1,t)=0,f(x,0)=0,D[1](theta)(0,t)=0,theta(1,t)=1,theta(x,0)=0};
 (5)
 > z:=0.98:
 >
 > sol:=pdsolve(eval([PDE1,PDE2]),IBC ,numeric, time = t): sol:-value(f(x,t), output=listprocedure); fN:=eval( f(x,t), sol:-value(f(x,t), output=listprocedure)):
 (6)
 > t := 1;
 (7)
 > A1:=x*R(z)*R(z)*(fN)(x, t);
 (8)
 > A2:=eval(int(A1, x))+C1;
 (9)
 > W11:=eval(subs(x=0,A2));
 > Find_c1:=solve(W11,C1);
 (10)
 >

Here u is fN(x,t) and t=1.

## How to integrate the computed values ...

Maple 18

Dear maple users,

A fine day wishes to all.

Here, we have computed the fN(x,t) value by using pdsolve.

We have to integrate the computed value and need to find the values with the sequence of x.

A1:=int(fN(x,1.12),x)

A2:=seq(A1,x=0..1,0.1)

How to integrate the computed values

And, How to find the values for the sequence of x.

 > restart:
 > with(PDEtools):
 > with(plots):
 > fcns := {f(x,t)};
 (1)
 > b1:=1.41:d:=0.5/1:xi:=0.1:ea:=0.5:ra:=2:
 > L:=z->piecewise(d<=z and z<=d+1, 1-2*xi*(cos((2*3.14)*((z-d)*(1/2))-1/4)-(7/100)*cos((32*3.14)*(z-d-1/2))),1):
 > PDE1 :=ra*(diff(f(x,t),t))=+b1*(1+ea*cos(t))+(1/(L(z)^2))*((diff(f(x,t),x,x))+(1/x)*diff(f(x,t),x));
 (2)
 > IBC := {D[1](f)(0,t)=0,f(1,t)=0,f(x,0)=0};
 (3)
 > z:=0.5;
 (4)
 >
 > sol:=pdsolve(eval([PDE1]),IBC ,numeric, time = t,spacestep = 0.025, timestep=0.0001): sol:-value(f(x,t), output=listprocedure);
 (5)
 > fN:=eval( f(x,t), sol:-value(f(x,t), output=listprocedure)):
 >
 > A1:= int(fN(x,t),x);
 (6)
 > A2 := seq(A1(x), x = 0.1 .. 1, 0.1);
 >

## How to execute the piecewise condition i...

Maple 18

Dear maple users

A fine day wishes to all

In my problem, L(z) is a piecewise condition.

L(z):

I have to calculate the f(x,t) value at x=0.71,t=1.12 and z=0.71 for L(z)=0..1.

How to calculate the f(x,t) value.JVB1.mw

 > restart:
 > with(PDEtools):
 > with(plots):
 > fcns := {f(x,t)};
 (1)
 > b1:=1.41:d:=0.5/1:xi:=0.1:ea:=0.5:ra:=2:
 > L:=z->piecewise(d<=z,1-2*xi*(cos((2*3.14)*((z-d)*(1/2))-1/4)-(7/100)*cos((32*3.14)*(z-d-1/2))),z<=d+1,1-2*xi*(cos((2*3.14)*((z-d)*(1/2))-1/4)-(7/100)*cos((32*3.14)*(z-d-1/2))),1);
 (2)
 > PDE1 :=ra*(diff(f(x,t),t))=+b1*(1+ea*cos(t))+(1/(L(z)^2))*((diff(f(x,t),x,x))+(1/x)*diff(f(x,t),x));
 (3)
 > IBC := {D[1](f)(0,t)=0,f(1,t)=0,f(x,0)=0};
 (4)
 > z:=0.71;
 (5)
 > sol:=pdsolve(eval([PDE1]),IBC ,numeric, time = t,spacestep = 0.025, timestep=0.0001): sol:-value(f(x,t), output=listprocedure);
 (6)
 > fN:=eval( f(x,t), sol:-value(f(x,t), output=listprocedure)):
 >