Mariusz Iwaniuk

787 Reputation

7 Badges

3 years, 228 days

Social Networks and Content at Maplesoft.com

MaplePrimes Activity


These are replies submitted by Mariusz Iwaniuk

@reza gugheri 

You should copy and paste all your code and definition of U to this thread.

Please paste copy&pastable code instead of screenshots. It is not fair to the people who are trying to assist to make them need to retype all your content based on some images.

@Stretto 

Solution for Numeric Fourier transform for sigmoid function.

For_sigmoid_function.mw

@Stretto 

 

My answer works for erf(x) function and if Maple can finds fourier transform symbolically, then works for general.

Give an example of a function for which a derivative can not be calculated symbolically ?

@9009134 

You can decrease steps in seq command to make plots more accucurate,but the calculation time will increase.


 

restart

Digits := 20

20

(1)

F := proc (s, x) options operator, arrow; exp(-(1/20)*sqrt(2)*sqrt(s)*sqrt(49*s^2+280*s+800)/sqrt(s+4))*exp((1/20)*sqrt(2)*sqrt(s)*sqrt(49*s^2+280*s+800)*x/sqrt(s+4))/((-exp((1/20)*sqrt(2)*sqrt(s)*sqrt(49*s^2+280*s+800)/sqrt(s+4))+exp(-(1/20)*sqrt(2)*sqrt(s)*sqrt(49*s^2+280*s+800)/sqrt(s+4)))*s)-exp((1/20)*sqrt(2)*sqrt(s)*sqrt(49*s^2+280*s+800)/sqrt(s+4))*exp(-(1/20)*sqrt(2)*sqrt(s)*sqrt(49*s^2+280*s+800)*x/sqrt(s+4))/((-exp((1/20)*sqrt(2)*sqrt(s)*sqrt(49*s^2+280*s+800)/sqrt(s+4))+exp(-(1/20)*sqrt(2)*sqrt(s)*sqrt(49*s^2+280*s+800)/sqrt(s+4)))*s) end proc

INVLAP := proc (F, tau, x) local oldDigits, n, r, k, t, result, Y, B, W, G; n := 80; oldDigits := Digits; Digits := oldDigits+max(80, 2*n); t := evalf(tau); Y := Vector(1 .. 2*n, proc (k) options operator, arrow; F(k*ln(2.0)/t, x) end proc); B := Matrix(1 .. n, 1 .. 1+n, proc (i, j) options operator, arrow; binomial(i, j-1) end proc); W := Vector(1 .. n, proc (k) options operator, arrow; (-1)^(n-k)*k^n*factorial(2*k)/(factorial(k)*factorial(n-k)*factorial(k)*factorial(k-1)) end proc); G := Vector(1 .. n, proc (k) options operator, arrow; add((-1)^r*B[k, r+1]*Y[k+r], r = 0 .. k) end proc); result := ln(2.0)*add(evalf(W[k]*G[k]), k = 1 .. n)/t; return Re(evalf[oldDigits](result)) end proc

INVLAP(F, 0.84e-1, 1/2)

-0.43468229756029945212e-11

(2)

plots:-pointplot({seq([x, INVLAP(F, 0.84e-1, x)], x = 0 .. 1, 0.1e-1)}, connect = true)

 

data := [seq([seq([i, j, evalf(INVLAP(F, i, j))], i = 10^(-9) .. 1, 0.5e-1)], j = 0 .. 1, 0.5e-1)]

plots:-surfdata(data, axes = frame, labels = [t, x, z])

 

``


 

Download INV-LAPLACE_-3.mw

@Melvin Brown 

For solving  PDEs use extreme powerfull pdsolve command ,will do the job for you.

@Zeineb 

Sorry Maple 2019 can't find a solution, give me an errors.

Run_code_2.mw

@Demo 

My solution  probably works  only in Maple 2019.

@Zeineb 

General solution for a=A,a=B:

General_solution.mw

@Lali_miani 

The short answer is that generally no, for your matrix B:=Matrix([[a, -b, e], [c, l, d], [-e, -k, m]], simplify command can't  simplify it. Mathematica also can't.

Matrix2.mw

 

@Preben Alsholm 

Thanks for clarification.

Intial condition: D[1](T)(x, 0) = 0 it's seems to be wrong ?

If I change to D[2](T)(x, 10) = 0(I assume),pdsolve(numeric) give me: Error, (in pdsolve/numeric) unable to handle elliptic PDEs.

Likely, that means Maple doesn't know a closed-form solution, if it exists.

@digerdiga 

"What do you mean by "trivial" corrections?"

 

I mean for a "trivial": unimportant fixes.

"Do you have an example and do you expect a large jump with 2019?"

 

I do not have it, and I do not know anything about it.

"Can you provide a list of a few "weaknesses" of int, that are going to be fixed?"

 

I do not have it, and I do not know anything about it.

 

English is not my native language,sorry for misunderstanding.

1 2 3 4 5 6 7 Last Page 1 of 20