## How Do I simplify the following equations...

I am new to Maple (I have Maple 11 student version) I tried to simplify atan(tan(x)) and nothing happens Also atan(sin(x)/cos(x)) does not simplify. What is the trick to simplification?

## creating DLL with cygwin...

Dear all: Inside maple, I want to call C program which is compiled using cygwin & gcc. I did a very easy one for testing. int _stdcall add( int num1, int num2 ) { return num1+num2; } and then gcc -o add.c && gcc -shared -o add.dll add.o However, this doesn't work. Maple continue to load the DLL forever...... Does anyone know the reason? I did it with Visual C++ with VC specific options and it works just fine. Thanks, Peter

## differential equation...

the equation y'=1-y(t)^2 how do you construct the de plot and find the equilibrium solutions

## A Solve Command in a Loop...

I want to have a solve command in a loop like this: for j from 0 to 10 do s[j]:=solve( {f[j]=0 , g[j]=0},[ a[j] , b[j] ]); od; where f[j] and g[j] are complex exponential functions of j and a[j]& b[j] e.g in a very simple case: f[j]:=a[j]*exp(I*2*j)+b[j] after such a loop Maple just solve s[0] and for other j's a warning message appears saying: "solutions may have been lost". And amazingly this warning seems very correct for when I put the solve command outside the loop,like solve({f[2]=0,g[2]=0},[a[2],b[2]]); it simply solves it! I don't know how I can overcome this problem?!

## How to animate fourier approximation of a function...

Hello, first post here, thanks for letting me on the forum. I am trying to visualize fourier approximation. This means that I want an animation of the several functions I get (the first only uses cos(x) and sin(x), the second one also uses cos(2*x) and sin(2*x)...) I managed to do this: [quote] restart;with(plots):f:=piecewise(-Pi

## The meaning of the parameters of the call_external...

When you call call_external like call_external(p1,p2,p3,p4) what do the four parameters mean?

## Differentiating a matrix...

Hi guys, do any of you know how to differentiate a matrix, i have the command A:=Matrix(2,2,symbol=k): I want to treat the elements k[1,1]..k[2,2] as variables, and then differentiate the matrix with respect to say k[1,1], and so on. How can i do this?

## ODE Analyzer...

I am using the ODE analyzer to look at the numerical solution to a second order ODE of the form 0=-uc'-kc+Ec" with u=.3, k=.0001 and E=10, and with conditions, c(0)=2 and c'(20,000)=0. When I try the solve numerically, I get an error message saying "unable to convert input to a first order system. Recieved error: too few boundary conditions, expected 5 got 2." What am I missing?

## solving PDE's...

I am trying to solve the following system of PDE's
dn := diff(n(x,t),t) = d*diff(n(x,t),[x,x])+n(x,t)*(r(n(x,t)+m(x,t)))*s[1](C[1](x,t))-n(x,t);
dm := diff(m(x,t),t) = d*diff(m(x,t),[x,x])+m(x,t)*(r(n(x,t)+m(x,t)))*s[1](C[1](x,t))-m(x,t);
dc1 := diff(C[1](x,t),t) = d[1]*diff(C[1](x,t),[x,x])+P[1]+(n(x,t)+m(x,t))*p[1](n(x,t)+m(x,t))+H*m(x,t)*p[1](n(x,t)+
m(x,t))-(P[1]+p[1](1))*C[1](x,t);

with initial and boundary conditions
IBC := n(x,0)=piecewise(x^2<1,0,x^2>1,1),m(x,0)=piecewise(x^2>1,0,x^2<1,1),C[1](x,0)=1,
C[1](infinity,t)=1,n(infinity,t)=1,m(infinity,t)=0,n(-infinity,t)=1,m(-infinity,t)=0,

## accessing lists...

I have made some lists named K[i], i= 1 to 48, with matrices, but this doesn't make maple happy, and I get 'Error, invalid subscript selector'. The problem is obvious that K[i] is taking element i in the list K, and I get problems when I want to take list K[i] and look at element j. So, how do you give lists names with indices?

## Show substitution values in Maple11 Tutor Integrat...

When Tutor suggests a 'change in variables' and next step is applied, is there a way to get Tutor to show the substitution for variable u as well? thanks

## Fixing display of math (gifs from MathML) in maple...

This is a new user question. mapleTA3.01 is installed on an Ubuntu linux server here at maths.uwa.edu.au and on SUSE linux at maths.curtin.edu.au across the river here. We have classes (around 1000 students at each institution) about to start soon and have been forced by the maple vendor to switch from AiM to mapleTA. (And, no worries, we will try. The March start date is scary.) We are having problems with most maple-type questions, displaying maths. Intermittently, the gif for the maths does not seem to get written. These are from the maplesoft Calculus questions. It isn't in anything peculiar