## 355 Reputation

12 years, 26 days

Thanks.

## guessing game...

If you meant to say that your v(r)

v:=r->((1/4*(3*(1-(R/a)^2)^.5-(1-(r/a)^2)^.5))/2);

then

plot(exp(v(r)/2),r=0..2e6);

will give you the desired plot.

## Where is v(r)?...

I do not see v(r). and certainly no r anywhere in your sheet.

restart
v:=(1/4*(3*(1-(R/a)^2)^.5-(1-(r/a)^2)^.5));
R:=1:a:=1:

plot(exp(v/2),r=0..2);

## Digits...

The issue was with the Digits.

For defualt digits, P(r) =

4.449669928*10^27

Digits:=50:

6.657168...*10^(-13)

Digits:=100:

7.2427...*10^(-64)

## Something wrong?...

When I use the value of `r` for which you claim that P(r)=0, I get

fsolve(rhs(sol), r = -5*10^6 .. 0, fulldigits)

evalf(subs(r=%,rhs(sol)));

4.449669928*10^27+0.*I

## syntax issues...

Like your previous post, you have repeated the mistakes.

1. There is no such thing as `refresh` instead you should use `restart`

2. You should not assign value to `Pi`. It is pre-defined in Maple with a Caps 'P'.

Now coming to your question which is unclear. Do you want to find the boundary condition first  and then solve the system of ODE's?

## Page #...

I got the book but unable to see the code for FDM. Could you please be more specific, like page number?

## You are right!...

The second part of my question (second question) is, Is there a more sophisticated way to implement FDM than the one i used?

## Sum...

We can avoid F(infinity) by using `Sum` instead of `sum` but still I am unable to reproduce any plot.

## Edit...

This will save some space and time.

Younes_Algo_Hellinger.mw

## syntax issue...

Apart from some basic syntax issues, the numerical PDE solve is unable to proivde a solution. But still you can have a general solution only for theta.

PDEs_solve.mw

## You are right about `Pi` but......

You are right about `Pi` but the function is correctly defined the Maple way.

As 2D-Maths input phi[2](xi):= sin(2*Pi*xi)^3 is the same as a Maple-input of phi[2]:=xi-> sin(2*Pi*xi)^3.

Question_(1).mw

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