Dear people in mapleprimes,

I have a question which is probably very elementary.

> integers:=[10..15]:
> select(isprime, integers);
Then, "Error, selecting function must return true or false" appears.

On the other hand, 

> integers:=[$10..15]:
> select(isprime, integers);

Then , [11, 13] appears.

What role does the character "$" play here? 

 Thank you in advance.

taro

Using the Fourier convolution theorem to solve f(t) =sin (t)

f(t)=R dJ(t)/dt+J(t)/C

R dJ(t)/dt+J(t)/C=f(t)

where f(t) is a driving electromotive force. Use the fourier transform to analyze this equation as follows.

Find the transfer function G(alpha)  then find g(t) .

 Thanks ....

Hi ;

I need your help to write the system contains all these equation:



# system 1
u[0,0]:=(1/2)*(u[1,0]+u[0,1]);
u[0,N+1]:=(1/2)*(u[0,N]+u[1,N+1]);
u[N+1,N+1]:=(1/2)*(u[N+1,N]+u[N,N+1]);
u[N+1,0]:=(1/2)*(u[N,0]+u[N+1,1]);
# system 2
for j from 1 to N do
u[0, j] := (1/4)*(u[1,j]+u[1,j]+u[0, j-1]+u[0,j+1]-f[0,j]*h^2);
end do;
# System 3
for j from 1 to N do
u[N+1, j] := (1/4)*(u[N, j]+u[N-1,j]+u[N+1, j-1]+u[N+1, j+1]-f[N+1,j]*h^2);
end do;
system4
 eqs := [ seq(seq(Stencil[1](h,i,j,u,f),i=1..N),j=1..N)];

How can collect these system 1 system2, system3 ans system4 in a set with one name.


sys:=[eqs,system3,system2,system2]; ( sys: here contains all the equation).

Thanks you.

Hi,

When I run two times my code, the results change.

Have you any idea, why???

Hi:

i will calculation of value function in every step by 0.001(x=0,x=0.001,x=0.002,...x=10):

my function:

f(x)=x^3+2*x+1

my domain:

0<x<10

Hi , everyone who love Maple and dsolve command, 

my ODE is :

sys_ode := diff(d11(m), m) = -(3*sin(m)^2-1)*d31(m)/a^(3/2)+(-3*cos(m)*sin(m)/a^(3/2))*d41(m), diff(d21(m), m) = (-3*cos(m)*sin(m)/a^(3/2))*d31(m)-(3*cos(m)^2-1)*d41(m)/a^(3/2), diff(d31(m), m) = -a^(3/2)*d11(m), diff(d41(m), m) = -a^(3/2)*d21(m)

using " dsolve([sys_ode]) " command could get the solution easily, and the solution contains "I" (imaginary domain).

However, when we substitute the solution into the ODE "sys_ode", find not correct !

we use the following command to check the solution :

 simplify(  -diff(d11(m), m) -(3*sin(m)^2-1)*d31(m)/a^(3/2)+(-3*cos(m)*sin(m)/a^(3/2))*d41(m)  )

the upper expression is supposed to be zero, but not ! Is it a bug in Maple dsolve ?

Hi:

how can i convert one nonlinear second order ode to first order in maple?

How can I plot multiple numeric plots, such that numeric solutions belong to different differential equations?

For solving problem sets, I have a pdf template I created for myself that has a header with a blank for the class name, TA, professor, date, etc. In addition to this header, I had a margin on the left to scribble questions I had and to holepunch. 

I used to print out the template and write on the template and turn in that as my pset.

I am nowthinking of doing everything on the computer. Writing out all of the problem set on the computer. Combining stuff from maple, combining handwritten stuff from the computer using a digitizer. However I want to write it all on top of the my template that I created, which is a pdf file. I can turn the pdf into an image file if need be. 

What would be the easiest way to do what I want? To open a program that automatically sets that pdf as the template and easily lets me handwrite stuff I want and paste in maple code? 

Right now if I tried my idea, I would basically be constantly copying and pasting stuff from maple and my digitizer drawn pictures/equations into one file and it would be very clumsy.

Basically there are problems that I do partially on maple and I just want to unify all my work into one easy, printable file. 

I'm doing a pset in maple.

I paste in a block of text in maple. I put an asterik at front and end, and hit enter and it spits out an error. Why? I thought two *'s around it comment it out. 

I also can't see the file I uploaded while I preview my post. 

Hai everyone.

I try to double integrate this generalized extreme distribution.

q[p] := 6.256: h := .8; t[c] := .45: S[di] := 0: k[v] := .32639: mu[v] := -0.1786e-1: sigma[v] := 2.1694: k[t] := .36132: mu[t] := .63543: sigma[t] := 3.1183:

int(exp(-(1+k[v]*(v-mu[v])/sigma[v])^(-1/k[v]))*(1+k[v]*(v-mu[v])/sigma[v])^(-1-1/k[v])*exp(-(1+k[t]*(t-mu[t])/sigma[t])^(-1/k[t]))*(1+k[t]*(t-mu[t])/sigma[t])^(-1-1/k[t])/(sigma[v]*sigma[t]), [v = q[p]/(2*h*t)+q[p]*t[c]/(2*h)+S[di] .. infinity, t = 0 .. infinity]);

however, I got an error, as follow:

Error, (in assuming) when calling '`root/fraction`'. Received: 'numeric exception: overflow'

Any recomendations and tips to solve this integration? or this integration may cannot solve?

Thank you.

I have an expression like this:

Since it is linear I want Maple to rewrite it into this:

(with the benefit that Maple then can solve it at least up to a point). i have tried to conceive a rule to do that but got stuck relatively quickly. Does anybody have a way to do this (in some genrality)?

Thanks,

Mac Dude.

Hi, I want to define functions recursively... 

I don't know how to do it with the for loop in Maple.

I have a[0](t)=0, a[1](t)=t, and then some recursion connecting a[j+1](t) = f( a[j](t), a[j-1](t)) for some explicit function f. 

Then I want to plot the graph of a[N](t) as a function of t. 

Thanks!!

Hi, please a Need a help.
I have an error in my code: Error, (in collect) cannot collect 0
Here, is the code:
Question8X.mw

Many thinks.