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I'm working on a complex problem in Composite Materials. I've gotten to a near-result 6x6 matrix, with several cells containing polynomial denominators. I have an equation for simplifying these, which boils the polynomials down to a single variable, but I can't seem to get it to substitute in. Can anyone help me solve this? The problem is also time-sensitive.

 

a problem of subs...

August 17 2014 taro 110

Hello people in mapleprimes,

 

I want to modify the next equation: 

(**)  a:=sigma*omega*alpha = mu(H, H)*s*omega*gamma1*L+mu(F, H)*s*L-mu(F, H)*s*L*gamma1;

to be

(***)    sigma*omega*alpha = mu(H, H)*s*omega*gamma1*L+(1-gamma1)*mu(F, H)*s*L;

 

For that, first I defined b as

b:=sum(op(k,rhs(a)),k=2..3)=collect(sum(op(k,rhs(a)),k=2..3),{s,L,mu(F,H)});

, and substituted this to a with

subs(b,a);

 

But, what I could obtain was only the orignal equation (**) not (***).

Please tell me how to use subs to this problem to obtain (***)。

Thanks in advance.

taro

P.S.

I know

(****)collect(lhs(a)=rhs(a),{s,L,mu(F,H)});

works well as for what I wrote (**) as above.

But, originally, it was a result from substituting various equations into an equation.

For it, (****) does not work well.  

 

 

Hi there

I'm taking my first steps with maple and my question is not exactly briliiant

Putting in a simple way, I'm trying to solve sth that looks like this

> li := a*[cos(7*x+8*x*y+9*y)*cos(-7*x-8*x*y-9*y)];
             a [cos(7 x + 8 x y + 9 y) cos(-7 x - 8 x y - 9 y)]

and i want to replace

with

getting (if i do it by hand)

> algsubs(7*x+8*x*y+9*y = 20*y, li);
                    a [cos(20 y) cos(-7 x - 8 x y - 9 y)]

my question, is there an elegant way to do it? sth that would look like this?

 

 

thank you for any tips

Hi There

I'm getting started with maple and facing a doubt about using subs, somehow it does not seem to work, this is my expression:

 

> restart;
> theta := omega*t-k*x;
                                omega t - k x
> phi[1] := -(1/2)*H*c*cosh(k*(z+h))*sin(theta)/sinh(k*h);
                   H c cosh(k (z + h)) sin(-omega t + k x)
                   ---------------------------------------
                                 2 sinh(k h)              
> diff(phi[1], t, t);
                                                             2
                H c cosh(k (z + h)) sin(-omega t + k x) omega
              - ----------------------------------------------
                                 2 sinh(k h)                  
> td := simplify(subs(z = 0, %));
                                                          2
                   H c cosh(k h) sin(-omega t + k x) omega
                 - ----------------------------------------
                                 2 sinh(k h)               
> simplify(subs(cosh(k*h)/sinh(k*h) = 1/tanh(k*h), %));
                                                          2
                   H c cosh(k h) sin(-omega t + k x) omega
                 - ----------------------------------------
                                 2 sinh(k h)               
I cannot subs cosh/sinh = tanh. I would like to know why.

Any tips? Thank you

So suppose in one maple worksheet, I run:

>assume(w, real); y:=2*w;
>save y, "test.m";

 
And then I open another, and run

>read "test.m";
>subs(w=1,y);

The substitution won't work, while it works if I don't make any assumptions about the variable w.  However, in the piece of code I'm actually running (this snippet is just to illustrate the problem), I need to make the assumption that w is real for solving a system of equations (otherwise maple seems to run out of memory).  Is there a way to save my result y in such a way so that I can make substitutions for w later?

Hi everyone,

I wanted to plot the fourier series up to a given order of a step function using the code I attached, to change the order I used a sum with upper boundary M. When setting M to a particular value and plotting the function the result is obtained within a second, when on the otherhand using plot(subs(M=11,...),...) it takes close to a minute to produce a picture.

This might be a misuse of subs, in any case, I wanted to share my experience and maybe get an explanation about why this takes that much longer.

Cheers,

Sören

restart

f := proc (t) options operator, arrow; sum(-4*sin((2*n+1)*t)/(Pi*(2*n+1)), n = 0 .. M) end proc

proc (t) options operator, arrow; sum(-4*sin((2*n+1)*t)/(Pi*(2*n+1)), n = 0 .. M) end proc

(1)

plot(subs(M = 11, f(t)), t = 0 .. 2*Pi)

 

M := 11; plot(f(t), t = 0 .. 2*Pi)

 

Download fourier_subs.mw

I wish to substitute Re=W[0]/V[0] in the expression V[0]/W[0] * diff(u(t),t). I tried using the subs command but it didn't work. Any help would be appreciated !

Help!!

Why do the first two of the following 4 examples not work in Maple 15?

subs(m=21,`mod`(m, 4));
subs(m=21,m mod(4));
                               21
                               21
`mod`(21, 4);
21 mod(4);

                               1
                               1
Is there a (simple) workaround?

Thanks.

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.

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