Hi, I am trying to plot a solution curve on a vector field with an initial condition of y(0)=0 and I keep getting error messages. This is what I have so far:

with(DEtools); dfieldplot(diff(y(x), x) = x^2+y(x)^2-1, y(x), x = 0 .. 5, y = -1 .. 5, arrows = line, title = 'Slope*Field');

Thank you.

Hi,

After upgrading to Maple 16.02, the Maple code:

eqn3:=diff(y(x),x)=x+sin(y(x));IC3:=[y(0)=2,y(3)=0];DEplot(eqn3,[y(x)],x=-5..5,IC3,y=-5..5,arrows=comet,linecolor=BLACK);

produces the directions field but fails to produce the solution curves.

I have tried the same code on two different machines running Maple 16.02 with identical results. I have also tried the code on Maple 16.01. In this case the solution curves are produced.

I have already solved my ODEs and used odeplot to analyse the change over time (0 to 10).

Below is my ODE,

d(a(t))/dt = x - y*(a(t))

d(b(t))/dt = m*a - n*(b(t))

My query here is,

I need to substitute a(t) and b(t) in a seperate equation,

h(t) = 60/0.98 * (a(t))*(b(t))

and i need to plot 'h' over time (0 to 10)

How do I go about doing this?

Please help.

Thanks.

Hey guys..

I need some help on determining the correlation coefficient between my data points for an Influenza epidemic and the SIR model, with my estimated parameters Beta and Alpha. The initial conditions for the equations are defined at the beginning of my worksheet:

SIR_model.mw

Hope someone can help me ;)

Hey guys

I am currently working on my final project in high school. This project is about mathematical modelling within epidemology, and i am currently working on the mathematical models based on the SIR model.

The basis models for the SIR model were pretty easy, but i cant figure out how to fit data to my models. My first idea was to use the method of Leastsquare and/or Nonlinearfit, but i cant figure out how to do this in maple.

Suppose X with two dots on the top +2*x with one dot on the top +3*x=4*t;x(0)=1; x with one dot on the top =2. using maple and Euler method approximate x(3.0) and x with one dot on the top (3.0) using a step size of h = 0.01. Edit your output to fit on one side of a single sheet of paper. Include Maple source code and circle the values for x(3.0) and x with one dot on the top (3.0).

numeric_de.mw

hello boffins

if my de was soluble analytically, I would get an expression of time in terms of the other variables (V,theta,x) easily, but because it is only numerically solvable, i get an expression x(t)=proc(t)...,- the variables V and theta are mixed up in it-. Is there anyway they can appear?

I know I can put numerical values on V and Theta (and x) and solve for time (using parameters...

Hi, I need help with graphing a certain logistics population model for an initial population size that is equal to 1.

dy/dt = k(1 - y/M)y k=2 M(t)=10e^-t/5 +3(1-e^-t/5)

So far I've worked out the values to input, but I don't know how to write it in Maple.

I know all I have to replace is the M in the dy/dt equation with these 2 values.

M(0) = 10

M(t goes to infinity) = 3

I'm trying to solve the following

> de := proc (omega, l, M) options operator, arrow; diff(y(r), `$`(r, 2))+(2*r-2*M)*(diff(y(r), r))/(r*(r-2*M))+(omega^2*r^2/(r-2*M)^2-l*(l+1)/(r*(r-2*M)))*y(r) = 0 end proc;

Hello,

I need to plot M vs phi from the following ode. For this I am using implicitplot but unfortunately

I am getting empty plot. Please guide me through this issue.

Thanks

eq1 := 1/(1-phi)^2.5/(1+4117/783*phi)*diff(f(eta),`$`(eta,3))+1/2*f(eta)*diff(f(eta),`$`(eta,2))

+M*(1-diff(f(eta),eta)) = 0;

bc:=f(0)=0,D(f)(0)=beta/(1-phi)^(2.5)*(D@D)(f)(0),D(f)(N)=1;

respar:=dsolve({eq1,f(0)=0,D(f)(0)=beta/(1-phi)^(2.5)*(D@D)(f)(0)},numeric,

Hi all,

I have a strange problem with the Classic worksheet in maple 15. To explain the problem i added an image.

when i want to plot vergl_6 without copying the equation i get an error. But when i just copy and paste equation 6 like i did everything works like i suspect.

Can anybody tell me the problem? I need to...

I adopted the approach suggested in an earlier post (http://www.mapleprimes.com

/questions/137320-Plotting-A-System-Of-Ode) for the known results,

but some part of curve is missing.

The output I got is

So I've got a numerical solution to a D.E. and want to find which parameters (v, theta) cause the second event to occur. Here's my dsolve

> soln:= dsolve({eqx, eqy, inty, intx, x(0)=0, y(0)=0}, {x(t), y(t)}, numeric, method = rkf45, output=listprocedure, parameters=[v, theta], events=[ [ [diff(y(t),t)=0, y(t)

The first event is "Does the trajectory reach its max at a height less than 3.05m? If so, stop computation"...

Hello every one,

I am using similarity transformation to transform a PDE into an ODE.

I got the ode but its in a very ambiguous (unclear) form.

I need help to have the ode in a more friendly reading format.

pdetoodest.mw

I wish to plot the trajectory of a ball, and I set up my three differential equations and solved them numerically. I can graph the x, y, z components but I can’t figure out how to plot 3D space curve of this (and animate it if possible).

I used dsolve, numeric rtk45, so the output is [t, x, x’, y, y’, z, z’] so I tried to assign the second (and 4^{rth} and 6^{h}) term in the list to a function

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