Thanks so much for your great answer!

x,y and z in my equations are not the XYZ coordinates, x represents the number of healthy cells, y represents the number of infected cells and z represents the number of immune cells. Here I wanted to show the phase portrait of healthy cells vs infected cells with field arrows.

Cheers,

Masoum

Hi there,

I just wonder if we can plot phase plane with arrows for more than 2 equations in Maple. For example:

DE:={D(x)(t)=y(t)-z(t),D(y)(t)=z(t)-x(t),D(z)(t)=x(t)-y(t)}

DEplot(DE,{x(t),y(t),z(t)},t=-2..2,[[x(0)=1,y(0)=0,z(0)=2]],linecolour=black,stepsize=0.1,scene=[x(t),y(t)],arrows=small)

This one doesn't give me a plot with arrows.

Thanks in advance for your assistance.

Regards,

Masoum

I am working on solving a very complex differential equation.  I believe I have a solution and am currently trying to check the solution I have to see if it is correct.  the method I am using right now is to assign all of the derived expressions to variables and then ask Maple if my solution satisfies the differential equation.  That is to say, I do something similar to the following:

x := solution :

One of the inputs I have to a solar vehicle model is the relationship between current and voltage for the solar panel. This relationship has been measured as 50 ordered pairs of current and voltage. As the model runs over time the value of voltage (and current) will change. Right now I have fit the I vs V data as a 6th order polynomial.

I would like if someone could help me with an example of the heat equation, this is lengthy so please bare with me.  When trying to recall your studies it is quite difficult to re-absorb all the different nomenclatures used by different people and put them into something you understand.  Some people use "c" for specific heat, some people use "s", some people use "a" for thermal diffusivity and some people use "k" which is also used for thermal conductivity. ...

Dear mapleprimes ODE enthusiasts,

I am analyzing a stiff 3D system characterizes by fast-slow dynamics. I believe I can show analytically that, for some parameter values, in a neighborhood of some critical points (where the system is stationary), the dynamic system has a local center manifold that is center-stable. I have simulated the system for different parameter values.I am interested in one particular trajectory. With a random set of initial values, the system...

Hi:

I have a worksheet with a fairly complicated expression. Suppose it is of the form A:=B.

In red I have

>A:=B;

and just below it, in blue I have

A:=B

Now I highlight the blue "A:=B", press CTRL-C, move to another worksheet, postion the cursor next to a blank ">" and press CTRL-V. The blue statement appears in the new worksheet, BUT...

It only appears in red (i.e. executable) if the blue statement "A:=B"...

What would be the best way to compute the determinant of a very large (millions x millions) 0-1 matrix?

I have a multi-equation vehicle model that I can set up as

> sol3 := dsolve([eqB, eqC, eqD, eqE, eqF, speed(0) = 0, V(0) = 0.7047824398e-1], [Tm(t), 

Tw(t), V(t), omega(t), speed(t)]);

or, following a MaplePrimes post

> sys := [eqB, eqC, eqD, eqE, eqF];
> ics := [speed(0) = 0, V(0) = 0.7047824398e-1, omega(0) = 0, Tw(0) = 0, Tm(0) = 0];
> vars := ...

Okay what am I doing wrong here?  It's an examination of the simple 1-d heat diffusion equation in a rod with homogenous boundary conditions.  I'm looking for the temperature distribution over a thin rod with unit length 1.  Both ends are held at 0.  And the initial temperature distribution across the rod I have set equal to x, with the diffusivity k=1/10.

So first set up the 1-d homogeneous heat equation
he:=diff(u(x,t),t)=k*diff(u(x,t),t,t):

I am looking for the equivalent command in Maple to the Mathematica command # which takes the first argument of a pure function. Is there any such equivalent, and if so what is it?

Hello friends,

I have tried to linearize three nonlinear equations which are coupled in the form of:

a1*xdot(1)+a2*xdot(2)+a3*xdot(3)=f1(x1,x2,x3)+u(1)

b1*xdot(1)+b2*xdot(2)+b3*xdot(3)=f2(x1,x2,x3)+u(2)

c1*xdot(1)+c2*xdot(2)+c3*xdot(3)=f3(x1,x2,x3)

the ai, bi, ci parameters are constant parameters and x1, x2, x3 are variables (states). also, u(1) and u(2) are inputs to the system. xdot(i) is the derivative form of xi.

I have a function written that takes a column vector and returns a column vector. I would like to apply this function to a matrix and have it run on the columns of the matrix. Is there a way to do this like in Mathematica? I have tried the Map and Map2 commands but they only apply a function entry by entry. I need a way to evaluate a vector function on the first through last columns of the matrix.

Hello,

I want to fit Data with a model that calculates the values by solving an ODE numerically.

solL:=dsolve({Lpde,ICS}, numeric, method=rkf45, parameters=[lambda[0],T[m]]);

Next, I created a procedure.

ans:=proc(p1,p2) solL(parameters=[p1,p2]); rhs(solL(3600)[2]); end proc;

This is giving a length L(t) depending on parameters lambda[0] and T[m]. I would like to fit this model with my data. These data are given for a fixed time...

I would like to know how to convert solution from rsolve 

rsolve({y(n+2)-2*y(n+1)+4*y(n), y(0)=C1, y(1)=C2}, y(n));

to this form with sin and cos