MaplePrimes - Maple 14 Posts and Questions

Boundary Value Problem, some iteration without evaluation

Thu, 29 Apr 2021 14:19:15 Z

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Download fourthLINEARBOUD042021.mw

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Download fourthLINEARBOUD042021.mw

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Download fourthLINEARBOUD042021.mw

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Download fourthLINEARBOUD042021.mw

PLS FIND ATTACHED A MAPLE CODE TO SOLVE SOME BOUNDARY VALUE PROBLEM, BUT IT JUMP SOME ITERATION WITHOUT EVALUATION WHICH END UP WITH INACCURATE SOLUTION.

> restart;
> with(LinearAlgebra);
> exp(1) := 2.7182818284590452354;
> alpha := .975;
> NULL;
> st := time[real]();
> for i to 4 do for j from 0 by .1 to 4-exp(1) do Exact[j] := evalf(ln(exp(1)+j)); Y[0] := proc (x) options operator, arrow; 1+x/exp(1)+(1/4)*((exp(1))^2-8*exp(1)+24*ln(2)*exp(1)-32)*x^2/(exp(1)*(16-8*exp(1)+(exp(1))^2))+(1/4)*(16*ln(2)*exp(1)-16-8*exp(1)+(exp(1))^2)*x^3/((-64+48*exp(1)-12*(exp(1))^2+(exp(1))^3)*exp(1)) end proc; Ics := Z(0) = 1, (D(Z))(0) = 1/exp(1), Z(4-exp(1)) = evalf(ln(4)), (D(Z))(4-exp(1)) = 1/4; f := proc (x) options operator, arrow; 0 end proc; p := proc (x) options operator, arrow; 0 end proc; q := proc (x) options operator, arrow; 0 end proc; r := proc (x) options operator, arrow; 0 end proc; u := proc (x) options operator, arrow; 0 end proc; eq[i] := diff(Z(x), `$`(x, 4)) = (1-alpha)*(diff(Y[i-1](x), `$`(x, 4)))+alpha*(-6*convert(taylor(exp(-4*Y[i-1](x)), x = 0, 20), polynom)); s[i] := dsolve({Ics, eq[i]}, Z(x)); Y[i] := unapply(op(2, s[i]), x); App[j] := evalf(Y[i](j)); Er[j] := abs(App[j]-Exact[j]); print([App[j], Exact[j], Er[j]]) end do end do; time[real]()-st;

Invalid Subscript selector - Maple 14

emendes — Sun, 18 Aug 2019 17:56:01 Z

Hello

The following maple command returns an error in Maple 14 (internal error in Typesetting ... "invalid subscript selector") but not in Maple 2017.

f:=(l::list)-> eval([y,y*z-x,-15*x*y-x*z-x],[x,y,z]=~l):

What did I miss?

Many thanks

Iteration formula

aminumustafa — Wed, 03 Jul 2019 16:36:13 Z

Download ITRATIVE.mw

PLS

HOW CAN I ITERATE THIS PDE IN THE FORM OF PICARD ITERTION.

ATTACHED IS THE MAPLECODE STARTED WITH.

Issues with eps exported files

Jaqr — Thu, 03 May 2018 15:37:51 Z

Hello,

Here is the code I used to generate the image:

densityplot(x,x=0..1,y=-0..0.1,colorstyle=HUE,style=patchnogrid,scaling=constrained,view=[0..1,0..0.1],axes=none);

Then, I exported the image in a eps format. When the file is displayed, white lines appear as a grid. The problem comes from Maple and not from the softwares used to visualize the image. I tried so many things to solve that but...

How to solve the problem?

Thank you.

Jaqr

Use of ATLAS in calculation of Riemannian metric invariants in case of minimal dependence on coordinates

Gideon Maschler — Sat, 07 Apr 2018 19:04:23 Z

I wish to calculate connection, curvature, Ricci curvature etc. for a

Riemannian metric given as follows: there is an orthogonal frame of vector

fields with stipulated Lie bracket relations between them. The frame is

orthogonal but not orthonormal, and the lengths of its vector fields are functions

of a single function on the manifold. Given these metric values on the frame and the

Lie bracket relations, the covariant derivatives are in principle computable from the

Koszul formula, hence connection and curvature are all determined.

When I try to define the metric using a dual coframe in ATLAS's Metric

routine, it allows me to define it but claims there is not actual curvature.

From the help it seems the coframes used in this routine are always given

as differentials of coordinates. Is there a way to get the metric via the data

given above without putting in by hand all the different Koszul formulas etc.?

How to display last few digits?

ganelon — Mon, 12 Mar 2018 09:02:30 Z

If I input 3^665 the whole number is displayed. How to display only last few digits?