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Dear all,

I would like to solve the Fredholm Integral equation, using numerical method.
This is my code.

there is a problem with subs, does not working here.
# Then, we obtain from (9) the coeficient A[n] and B[n].

Then I woulk like to recompute (2), and then compute (1).
# Puting x=m*h, in (1), how can we generate a linear Matrix from (1).

 

Fred.mw

Thanks

I want to find the solution in a special form.
How can I do it?
Here is what I tried:

(Maple)

(Maple)


In the left hand side u_1 is not changed in  D(u_1).
I want to substitute and evalute (differentiate) it.

Thanks,  Sandor

 

 

 

 

Hi everybody,

Suppose that in an equation, I have the term x/(t).  I want to substitute it by v(t).  Any suggestion because I am trying but don't find an help page on this.

 

Thank you in advance for your help!

 

--------------------------------------
Mario Lemelin
Maple 17.01 Ubuntu 13.10 - 64 bits
Maple 17 Win 7 - 64 bits messagerie : mario.lemelin@cgocable.ca téléphone :  (819) 376-0987

Hello, I have different values to substitute into my theta in a matrix. I tried to use the subs function but the results came out are all dashes. Have you any idea how to fix it please?

AA:=RandomMatrix(3,5);
BB:=map(cos,AA*theta);
CC:=RandomMatrix(3,5);

I tried method 1:

subs[inplace](theta=CC,BB);

Method 2:

DD:=Matrix(3,5);
for m from 1 to 3 do
for n from 1 to 5 do
DD(m..m,n..n):=subs(theta(m..m,n..n)=CC(m..m,n..n),BB(m..m,n..n));
end do:
end do:
DD;

Thank you.

The following integral is solved easily via a substitution. Why does Maple not evaluate it?


int(tan(x)^(1/3)*sec(x)^2, x)

int(tan(x)^(1/3)*sec(x)^2, x)

(1)

int(surd(tan(x), 3)*sec(x)^2, x)

int(surd(tan(x), 3)*sec(x)^2, x)

(2)

``


Download intsub.mw

Greetings,

I have a differential equation:

an the solution:

I want to substitute

ekf := omega = sqrt(c/m);


algsubs(ekf, sol);
but sol does not change.

This works a bit but does not substitute everything in a way that you would expedect

This is the result:





Thanks in advance

I was doing some practice problems for Maple, when I encountered this problem:

 

My code is

 

w:=x+2+sin(x+2);

subs(x+2=u,w);

 

The output however did not change both `x+2`'s into `u`.

 

The output was: x+2+sin(u)

 

Any ideas as to why? Thanks in advance.

Hi,

The subs command is not working properly for Vector type, see worksheet.

I can use simplify instead, but that's not what I really wanted.

Download vsubs.mw

 

Casper

Hi all,

I am having some problems when solving high order polynomials. When oders are 'high' and systems involve multiple variables, Maple is slow to do so.

See in worksheet for detailed codes.

slow.zip

kappa - gives the vector that i am interested in

sC - a reparameterisation which has 'summation' in it

Aim is to verify that it works (it should!)

I currently ask...

Hi,

Say for a 126 by 18 symbolic matrix, substituting numerical values into the matrix DD1 takes about 10 seconds (using time() );

for a 62 by 16 matrix, take just about 1/5 second.

By when the matrix is about 254 by 20, it take much longer! More than a minute!

I never actually waited how long, but I am wondering if there is something wrong? Am I using the right command?

Say the matrix is DD1 with numpar:=[x=0.3,y=0.2,z=0.98,....]

I'm using Maple to come up with equations, and then I'm substituting in variable names for functions which I can then output to Matlab.

I haven't had any problems until I ran into partial derivates described by the D[] operator.  For example, if i have a function f described by f(x(t),y(t)) and I differentiate it wrt t, I get 

D[1](f)(x(t),y(t))*(x(t)_dot) + D[2](f)(x(t),y(t))*(y(t)_dot)

I want to make a substitution for D[1](f)(x(t),y(t)) and D[2...

Working.mw

This one is wokring fine.

 

However,

 

See the new worksheet: testP.mw

with the source code: tmP.c

######################################################################...

Hi,

 

> seq(seq(p[j,c],j=2..3),c=1..3)=seq(seq(1/(1+exp(-(mu+cat(tau,j)+cat(eta,c)+mix[j,c]))),j=2..3),c=1..3);

Basically, I want to use these expressions in subs.

How do I tell Maple to make the substitution of "lhs=rhs"?

(in the form of {p[2,1]=something,p[3,1]=something,p[2,2]=something,p[2,2]=something,p[2,3]=something,p[3,3]=something,})

I can then use subs() to replace them in my desired expression.

Casper

Hello,


I have an awfully complicated expression depending on three variables m1, m2, m3 and a lot of parameters. When I try to substitute m1, m2 and m3 by 0, 0 and 1 respectively, m1, m2 and m3 are effectively replaced but lots of (0)s and (1)s appear after some of the parameters (and even 0(0), 1(0), 1(1), 0(1)...)

What does this mean and how to avoid it? Following is an example of the problem.

Instruction:

In the solution set linked to above, I would like to replace each instance of the constant sqrt(k*(m[2]+m[1])/(m[2]*m[1])) with ω. I feel that this should be possible with algsubs, but cannot figure out the proper...

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