Hi,

Anyone knows how to define a ring of polynomials with variables x_1,...,x_n such that x_i*x_j = -x_j*x_i if i \neq j?

I tried using the Physics package and AntiCommutator but the problem is that in that case the variables anticommute with themselves so I have x_i^2=0.

If there is no direct way to this, I guess I could define a procedure that would look at the monomials of a polynomial and order them in lexicographic order and each time it switches two variables with different index it would multiply the monomial by -1.

I also don't know how to do that since I don't know how to look at a specific term in a monomial. For example, if my monomial is x_ix_jx_k, is there a way to find the first two variables and then switch them if LexOrder(variable1,variable2)= LexOrder(x_i,x_j)= false, i.e. if i>j?

Thanks,

M-A

Hi there,

I used the following plot command in maple13.

with(plots):

implicitplot(abs(x)+abs(y)=2, x=-2..2, y=-2..2, scaling=constrained)

But the output(square) is not complete at vertices.In fact at the vertex the graph is like a trapezoid.

Any help will be appreciated.

Yegan

For different reasons I need to ocasionally export a number of Maple worksheet in a folder to pdf files. Is there a way to automate this? I would want that the worksheet is opened, output removed, then executed and eventually exported to pdf. It can take quite a while to do this manually for about 50 worksheets.

Dear people in Maple primes,

Please tell me why algsubs would not work well in the following case.

algsubs(-eta*M[n]/(gamma*(eta*M[n]+gamma))-1/(eta*M[n]+gamma) = factor(-eta*M[n]/(gamma*(eta*M[n]+gamma))-1/(eta*M[n]+gamma)), (-eta*M[n]/(gamma*(eta*M[n]+gamma))-1/(eta*M[n]+gamma))*p[i]+(int(p[i], i = 0 .. M[n]))*eta/(gamma*(eta*M[n]+gamma))+alpha/(eta*M[n]+gamma));

Following error message appeared when the above code is executed:

Error, (in algsubs) cannot compute degree of pattern in eta

Best wishes.

taro

HI, dear all. When I tried to use the plot option 'adaptive' to make my plot more smooth and realistic, I encountered the following erro. I cannot understand why. From the help guide, I learn that adaptive can be assigned n or true or false, but errors appeared.  Thanks for your help.

> implicitplot(-x^3+3*x+a = 0, a = -3 .. 3, x = -4.0 .. 4.0, view = [-3 .. 3, -4 .. 4], adaptive = 2, resolution = 1000, numpoints = 2000);
Error, (in plot/options2d) unexpected option: adaptive = 2
> help("adaptive");

Hello
I encountered with a problem in understanding of structured types. I test following structured types:



the result is

true
false
false

I cannot understand two last results as I expected to receive trues. Could you explain me the result?
Thank you.

UPD
A code appropriate for copy/pase along with short problem solution is presented below

restart;
`type/A1`:={integer, rational};
`type/A2`:=integer or rational; #  it matchs the expressions that literally contain `or` (see @Carl Love's
answer below)
`type/A3`:=OR(integer, rational); # `Or` should be used rather then `OR` (see @acer's
answer below)

x:=5;
type(x, A1);
type(x, A2);
type(x, A3);

> restart;
> with(plots);
> Eq1 := diff(f(eta), eta, eta, eta)+f(eta)*(diff(f(eta), eta, eta))-2*(diff(f(eta), eta))^2-M^2*(diff(f(eta), eta)) = 0;
/ d / d / d \\\ / d / d \\
|----- |----- |----- f(eta)||| + f(eta) |----- |----- f(eta)||
\ deta \ deta \ deta /// \ deta \ deta //

2
/ d \ 2 / d \
- 2 |----- f(eta)| - M |----- f(eta)| = 0
\ deta / \ deta /
> Eq2 := 1+(4/3)*R*(diff(theta(eta), eta, eta))+Pr*(f(eta)*(diff(theta(eta), eta))-(diff(f(eta), eta))*theta(eta)) = 0;
4 / d / d \\
1 + - R |----- |----- theta(eta)||
3 \ deta \ deta //

/ / d \ / d \ \
+ Pr |f(eta) |----- theta(eta)| - |----- f(eta)| theta(eta)| = 0
\ \ deta / \ deta / /
> bcs1 := f(0) = S, (D(f))(0) = 1+L*G, (D(D(f)))(0) = .1, f(6) = 0;
f(0) = S, D(f)(0) = 1 + L G, @@(D, 2)(f)(0) = 0.1, f(6) = 0
> fixedparameter := [S = .1, M = .1];
[S = 0.1, M = 0.1]
> Eq3 := eval(Eq1, fixedparameter);
/ d / d / d \\\ / d / d \\
|----- |----- |----- f(eta)||| + f(eta) |----- |----- f(eta)||
\ deta \ deta \ deta /// \ deta \ deta //

2
/ d \ / d \
- 2 |----- f(eta)| - 0.01 |----- f(eta)| = 0
\ deta / \ deta /
> fixedparameter := [R = .1, Pr = .7];
[R = 0.1, Pr = 0.7]
> Eq4 := eval(Eq2, fixedparameter);
/ d / d \\ / d \
1 + 0.1333333333 |----- |----- theta(eta)|| + 0.7 f(eta) |----- theta(eta)|
\ deta \ deta // \ deta /

/ d \
- 0.7 |----- f(eta)| theta(eta) = 0
\ deta /
> bcs2 := theta(0) = 1+T*B, (D(theta))(6) = B, theta(6) = 0;
theta(0) = 1 + T B, D(theta)(6) = B, theta(6) = 0

> T := .1; B := .1;
0.1
0.1
> L := [0., .1, .2, .3];
[0., 0.1, 0.2, 0.3]
> for k to 4 do R := dsolve(eval({Eq3, Eq4, bcs1, bcs2}, L = L[k]), [f(eta), theta(eta)], numeric, output = listprocedure); Y || k := rhs(R[2]); YL || k := rhs(R[3]) end do;
Error, (in dsolve/numeric/bvp/convertsys) too many boundary conditions: expected 6, got 7
> plot([YL || (1 .. 4)], 0 .. 6, 1 .. -.2, labels = [eta, diff(f(eta), eta)]);

Hi

I'm trying make Maple write the actual result, when i differenting an expression: x[s] := x(t)+sin(theta(t))*a.
when i differentiate with respect to t, i get:

> diff(x[s], t);
=
print(`output redirected...`); # input placeholder
/ d \ / d \
|--- ()(t)| + cos(theta(t)) |--- theta(t)| a
\ dt / \ dt /

Maple, writes the expression as a table, but i need to see the normal function? Why does it do that? And how can i make it show the expression as a normal function?

When i derive the two parts serperately i get the normal result, but as soon as i add them together, i get the table rasult again?

Is there an easy trick for this one?

-Nicolai

Hi,

  I have a file "d:\\test.txt", the content is 

       1, 2.0000 + 0. I

then I use

f:=readdata(`d:\\test.txt`,2);
for i from 1 to 1 do
print(i,f[i]);
end do:

it gives me

***

[[1.]]
1, [1.]

 ***

If I remove the comma in the file, I could obtain 2. I do not want to do it manually that remove all commas by hand. Is there any way to skip the commas in readdata?

Consider the function

The above definition may result in four cases depening on r and x.

Can Maple calculate automatically all possible cases and the corresponding Maxima, Minima and Values at intervals limits?

I have two lists with differential monomials, like this: [y'y'', y''', (y'')^2].

List is rather big, i want to check if one such a list contains in other.

Seems to be that there is some internal procedure for this operation.

But I don't know what it is...

Nm= p1.
p2 ...pm + 1, for m more than or equals 1.

So N1 = p1 + 1 = 2 + 1 = 3, N2 = p1 p2 + 1 = 2
3 + 1 = 7, etc.

We prove that Nm is not divisible by any of p1, p2, . . . , pm, so that Nm is either a prime or it is divisible by a prime larger than pm.

(c) Use Maple to find out which of these numbers Nm, for m = 1, 2, . . . , 15, is actually prime.

Use Maple to compare pm with the smallest prime number that divides Nm, for m =1, 2, . . . , 15.

So I am brand new to using Maple and am trying to solve a system of ODE's. When I try and use dsolve however I reciever the error "function expected" and I am not sure why. The code I have is as follows

sys_ode := diff(A(t), t) = a*(A(t)+B(t))-b1*A(t)*(C(t)+D(t))-g1*A(t)*B(t), diff(B(t), t) = -b2*B(t)*(C(t)+D(t))+g1*A(t)*B(t), diff(C(t), t) = e*(b1*A(t)+b2*B(t))*C(t)-g2*b2*C(t)*B(t)-g3*C(t)*D(t), diff(D(t), t) = g2*b2*C(t)*D(t)-m*D(t)

dsolve([sys_ode])

I'm sure it is something simple, but I just can't seem to figure out where the issue is. Any help is much appreciated.

I'm trying to substitute one Differential equation into another differential equation.

eq1:=d*n(t)/dt = (rho(t)-beta)*n(t)/Lambda+lambda*C(t)+q

eq2:=diff(eq1, t)

resulting in -> eq2 := d*(diff(n(t), t))/dt = (diff(rho(t), t))*n(t)/Lambda+(rho(t)-beta)*(diff(n(t), t))/Lambda+lambda*(diff(C(t), t))

then I'm given that (diff(C(t), t)) is given by another equation: 

eq3:=d*C(t)/dt = beta*n(t)/Lambda-lambda*C(t)

At this point I'm trying to substitute equation 3 into equation 2 for diff(C(t),t)

eq4 := subs(diff(C(t), t) = rhs(eq2), eq5)

however no matter what way's I try this I get an error: 

Error, (in simpl/reloprod) invalid terms in product: (d*(diff(n(t), t))/dt = (diff(rho(t), t))*n(t)/Lambda+(rho(t)-beta)*(diff(n(t), t))/Lambda+lambda*(diff(C(t), t)))^-1

I then tried to map it but again i got an error specifically about the first parameter: 

Error, invalid operator parameter name

eq5:=map((d/dt C(t))->beta/Lambda*n(t)-lambda*C(t),eq2)

I'm just wondering if what I am trying to do is even possible in Maple? 

If anyone can help I would greatly appreciate it! 

The system :