I can't solve this problem, can someone explain me whats worng and how to fix it, here is what i've done:

with(plots);
with(DEtools);
sist := diff(x1(t), t) = -4*x1(t)+x2(t), diff(x2(t), t) = -x1(t)+7*x2(t);
    d                             d                          
   --- x1(t) = -4 x1(t) + x2(t), --- x2(t) = -x1(t) + 7 x2(t)
    dt                            dt                         


condi := [x1(0) = 0, x2(0) = 3], [x1(0) = 2, x2(0) = 1], [x1(0) = 7, x2(0) = 9];
        [x1(0) = 0, x2(0) = 3], [x1(0) = 2, x2(0) = 1],

          [x1(0) = 7, x2(0) = 9]
for i to 3 do sol[i] := dsolve({sist, condi[i]}, {x1(t), x2(t)}, numeric); gra := odeplot(sol[i], [x1(t), t], t = -1 .. 1); display(gra) end do;

http://www.gap-system.org/Manuals/doc/ref/chap50.html

which group do four differential electromagnetism belong to in library available in gap system? 

what is the order of the group?

do maple 17 have this group? how to show?

I'm currently having some difficulties in solving a system of differential equations numerically.

This is my code.

how to generate random data from equations of electromagnetism?

how to call matlab to run k means on the data and

how to show which circle do the row of data belong to?

is there a built in function which calculates the radical of a number?

e.g. 54=2*3^3

rad(54)=2*3=6

Dear Friends:

I am currently working on a calculation for phase velocity of acoustic waves and don’t get along.  

My equation has the following form:

equ := tan( (31 / 20000) * sqrt( -9610000/c^2 + 1) / Pi) / tan((961/1260000) * sqrt( -39690000/c^2 + 1)/ P i) = -(1191640000/63)*sqrt(-9610000/c^2 + 1)*sqrt (-39690000/c^2 + 1)/ (c^2*(19220000/c^2 - 1)^2)

Using ‘sol = solve(equ,c)’ returns

sol := 96100* RootOf(1 + (400000000 * Pi^2 * RootOf(40320000000000000000 * Pi^4 * tan(_Z)*_Z^4256000000000000 * Pi^3 * csgn(_Z) * _Z^3 * tan((1/157500) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167) / Pi) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167) -96868800000000 * Pi^2 * tan(_Z) * _Z^2 + 615040000 * Pi * csgn(_Z) * _Z * tan((1/157500) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167) / Pi ) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167)+58181823 * tan(_Z))^2 - 961)* _Z^2)

c should be in a range of 13,000.

Two questions:

1) How can I deal with _Z?

2) Any suggestion how I can calculate ‘c’? Maybe numerical?

I am relative new in maple…

Many thanks!

Alex

Hi,

Might be a silly question but how do I preview/display the expression I type instead of maple automatically solving it.

For example, If I type in '1+1' in wolfram, it displays 'input: '1+1'' right below it.

I would like to do this in maple but cant seem to figure it out.

Hopefully that made some sense.

Cheers and thanks! 

Let I=<3x^2+2xy+x, y-xy+3, y^2-2x+4> be a polynomial ideal in K[x,y]. I want to form a matrix M corresponding to this ideal as the following:      

                                 x^2     xy     x      y^2      y      constant

                               -----     ----   ----    ----     ----     ------

                                  [3       2       1       0       0           0]

                             M= [0      -1      0        0       1           3]

                                  [0       0     -2        1       0           4]

Please note that in the first, the all monomials appeared in generators of I,  sorted by lexicographic ordering x>y. How can I from matrix M from polynomial I?

Hello,

  I have a complicated task. Suppose there is a file, its content is

1

A    3
0.8 0.2

0.6 0.3

0.5 0.4
****
2
A   3

0.8 0.2

0.6 0.3

0.5 0.4

****

  I want to read the file for each line, and store the content in each variable, e.g. "S" and 3 for two different variables, respectively. 

By using 

Nn:=readline("file");
Nn2:=readline("file");
Nn3:=readline("file");

parse(Nn);

parse(Nn2);

For N2, it does not work "Error, incorrect syntax in parse: unexpected number (near 6-th character of parsed string)"

How to read such a file properly including varies of content? Thanks a lot!

Int(piecewise(t < T1, exp((1/2)*t*(1+2*I-I*sqrt(3))), t < T2, -1000*exp((1/2)*t*(1+2*I-I*sqrt(3)))*(-1/1000+T1-t), T2 <= t, -1000*exp((1/2)*t*(1+2*I-I*sqrt(3)))*(-1/1000-T2+T1)), t)

The help of maple software is not so clear , and I cant understand the exact way which leads to exporting a matrix from maple to matlab. more precisely how I can link between maple and matlab .

would you please with an example show me the rule.

I just wanted to ask whether one can get out of the expansion

(D-f(x))@@2(g)(x)=(D@@2)(g)(x)-(D((f(x))(g)))(x)-((f(x))(D(g)-(f(x))(g)))(x)

the intended result

(D@@2)(g)(x)-D(f*g)(x)-f(x)*D(g)(x)+f(x)^2*g(x)

Here is a simple example to explain my problem:

I would like to have a break after the first graph and with return

the loop shoul continue to the next and so on.

Thank you for your help!

Test:=proc()

    plot(x^j,x=-2..2):

end proc:

for j from 1 to 3 do

   Test()

end do;