I am trying write a code for this question at here 

https://math.stackexchange.com/questions/170319/how-many-triangles-with-integral-side-lengths-are-possible-provided-their-perim/170325#170325

but I got the wrong answer. This is my code.
 

restart; 
L := []; 
for a to 18 do
 for b to 18 do 
for c to 18 do 
if a < b+c and b < a+c and c < b+a and a > abs(b-c) and b > abs(a-c) and c > abs(a-b) and a+b+c = 36 then
 L := [op(L), [a, b, c]] end if end do end do end do;
 nops(L); 
L

I got 136 triangles. This is a wrong answer. How can I repair my code?

how I can pdsolve these equations?

moadelat.mw

Download moadelat.mw

I have multiple accounts. I would like to delete them. Please tell me how to delete it. Thank you.

How can I plot functions Vc=(0.5+t)^n

with t=z/h, 

Hai any one help me to plot the curves and remove the errors  i am attaching the codes and  sample graph. thanks in advanced.
 

test.mw

Hi all,

I'm struggling with solving a delayed differential equation with time-dependent delay.

I have already use dde solver with matlab and find it cannot reaches my numerical accuracy. 

Does maple can solve this problem? I explore a little bit and don't find there is a document to guide how to tackle with this problem.

Constant delay cannot solve my problem.

Thank you very much,

Peter

Is there a solve(identity ...) command for systems? I have 4 identities in the variable t.
They are Q1, Q2, Q3, Q4. I try solve(identity(Q1,Q2,Q3,Q4),t), A, B, C, D), and other forms of it, but
nothing works.
Thank you!

maplatha
 

I solved an ODE numerically. Code: question_(2).mw

delta*(M(t)*diff~(X, t$2)+C(t)*diff~(X, t))+K(t)*X=f(t)

How to calculate X(t) for different values t and to create a table like following. 

I tried to solve an equation with a A0^2*v0 + .....................= 0 with 0 as a subscripted Index. The value of A0 was 0.35.

Maple returned the result with 0.350 as a variable with subscripted 0 and no numerical result.  When changing the variable to A0 without subscripted index 0 Maple returned the numerical result correct.

Hi there!

I am trying to calculate Eigenvectors of Matrices, Maple does not seem to understand that, however. I have used the structure of the example in the "help" section

A := `<|>`(`<,>`(-1, -3, -6), `<,>`(3, 5, 6), `<,>`(-3, -3, -4));
v, e := Eigenvectors(A) 

and even the example itself, it doesn't work. Maple always responds with   

"Error, (in Matrix) triangular[] storage expects name parameters"

What can I do?

I am trying to do taylor series expansion around the critical point, but I keep getting an error, because I think Maple is taking my critical point as function {x(t) = 5, y(t) = 10}. I would like to get just the output of x(t)=  from the list of critical points. Ex. Does anyone know the maple code to get "5" and "10" from the list of critical points without typing in 5 and 10.

Hi guys;

can one please show me how to plot graphs in on layout. i want like soundalgekar2004-deka.pdf using this code

variable.mw
 

Download variable.mw

3.mw Here is my maple code that shows the animation for different values in b. The equation this is referring to is given in the code. I have done (b) and (c), and the animation is in the code, but I am not sure where for what value of b for the behavior changes, any tips on what to look for would be really helpful.

However, I am primarily concerned with (d) as I am not sure how to demonstrate periodic behaviour with dsolve. Thanks for the help!   

Hi, 
So I am trying to use Maple to find the integer points in a region(s) bounded buy a set of inequalities. But for a specific set of inequalities, in four variables,
inequalities:= [-a1-a2+a3+a4 <= 2, a1+a2 <= 3, -2*a1 <= -1, -2*a2 <= -1, -2*a3 <= -1, -2*a4 <= -1, -a1+a2+a3-a4 <= 4, -a1+a2-a3+a4 <= 4, a1-a2+a3-a4 <= 4, a1-a2-a3+a4 <= 4]; in four variables, vars :=[a1,a2,a3,a4];

I am getting the following error
Error, (in solver) invalid input: LinearMultivariateSystemInternal expects its 1st argument, eqns, to be of type ({list, set})({`<`, `<=`, `=`}), but received {a1-a2 = 0, -11/2+a1 <> 0}

Also, upon checking the inequalities by hand, I am sure that the region mentioned in the error doesnt come up. as based on the inequalities, it is not possible to have -11/2+a1 > 0. But though I could be wrong about my manual inequality analysis, the error is still suprising and worrying. 
Another point to note is that if I do a variable change, as
t1 := a1-a2;
t2 := a1+a2;
r1 := a3-a4;
r2 := a3+a4;
Then with new variables the inequalities are solved without any errors.

I am working with Maple2018 for this problem. 

Any help or insight into the root of this problem would be a lot of help.