Items tagged with differentialdifferential Tagged Items Feed

Error / differential equation system...

March 29 2014
0 1

Hi,

What is the reason/Why:

Error, (in dsolve/numeric/bvp) unable to achieve requested accuracy of 0.1e-5 with maximum 128 point mesh (was able to get 0.66e-1), consider increasing maxmesh or using larger abserr

Thanks for the help :)

Differential Equations - Quasi Period...

March 20 2014
1 3

Hi, can I get some help with this?

The question is:

Consider the following IVP for a mass of m = 2 kg attached to a spring with a spring constant k = 9 N/m. The spring mass system is in a medium with damping constant b.

2y" + by' + 9y = 0

y(0) = 0, D(y)(0) = -3

It then asks find three values b1, b2, b3 where b1 is underdamped, b2 is critical, b3 is over.

I set b1 as 1, b2 as sqt 72, b3 as 9.

Then it asks to find the quasi period.

I can't get my quasi period right. My answer is 2pi/ sqrt (4.5).

Any help?

problem with diff and D...

March 09 2014
0 0

hi,i want to take differential with respect to another differential using physics package,but using D instead of diff,could anyone help me do that ? for example :

restart; with(Physics):
A1 := -(1/24)*1*rho*((diff(phi[1](x, t), t))^2)*(h^3)-(1/2)*1*rho*((diff(u[ref](x, t), t))^2)*h-(1/2)*rho*((diff(w(x, t), t))^2)*h+(1/24)*1*1*((diff(phi[1](x, t), x))^2)*(h^3)+(1/2)*1*(1*((diff(u[ref](x, t), x)+(1/2)*(diff(w(x, t), x))^2)^2)+K*1*((diff(w(x, t), x)+phi[1](x, t))^2))*h-1*q*w(x, t):

A2:=-diff(diff(A1,diff(u[ref](x,t),x)),x);

here i want to compute A2 using D command,not diff and i do not want use convert command ! i just need to calculate A2 directly using D command. tnx for your help.

Nonlinear DE - Need hints on how to solve...

March 03 2014
1 1

I have the following nonlinear Differential Equation and don't know how to solve.  Can anyone give me any hints on how solvle for E__fd(t).  I don't even know the specific classification (other than nonlinear) of this DE can someone at least give me hint on that. Thanks.

.5*(diff(E__fd(t), t)) = -(-.132+.1*e^(.6*E__fd(t)))*E__fd(t)+0.5e-1

Thanks,

Melvin

How do I solve this system of PDEs in Maple?...

February 13 2014
1 3

Hi there,

I'm quite new to Maple so please forgive me! I have a system of partial differential equations I'm trying to solve in Maple as such below

df/dt = f(1-f) - f * h

dg/dt = g(1-g) * Gradient(1-f * gradient(g))

dh/dt = (g - h) + Laplacian(h),

where f,g,h are functions of space and time (i.e. f(x,y,z,t)). I guess my first question is - is this possible in Maple to evaluate? (I'm currently unsure on ICs as I'm figuring it out from the model - it's a model for cancer growth I'm trying to evaluate but have a rough idea of what I'd use).

If it is possible, can you please share how I'd write this? Everytime I've tried I seem to be failing to define anything properly, so your expertise would be greatly appreciated!

Incorrect first argument error...

January 21 2014
1 4

I'm attempting to plot several solutions of this differential equation (I have uploaded my worksheet). I have used this series of commands before without issue, but for some reason I keep getting the error message: "Error, (in plot) incorrect first argument" ect.. Does anyone have any insight into what might be going wrong? Thank you.

Download ass_1_#9.mw

ass_1_#9.mw

How to solve nonlinear equation numerically in Map...

December 20 2013
1 3

restart;

diffeq := diff(w(r), $(r, 1))+2*beta*(diff(w(r), $(r, 1)))^3-(1/2)*S*(r-m^2/r) = 0;

con := w(1) = 1;

ODE := {con, diffeq};

sol := dsolve(ODE, w(r), type = numeric);

How can i have numerical solution of the above differential equation with corresponding boundary condition?

how i can get a single associated Legendre functi...

December 19 2013
1 0

hi,

there is a common  differential equation in my maple note,the solution of the eq. can be expressed by

associated Legendre function(s),but i get a result by hypergeometric representation.how i can translate the later into a  single Legendre fun？

Thank you in advance

 >
 (1)
 >
 (2)
 >
 (3)
 >
 (4)
 >

Download question_12.19.mw

Events in dsolve...

December 16 2013
1 5

Hi

I  have a system of second order differential equation to be solved numerically. I would like to set up events to halt integration  to find the values of phi when r(phi)=2/3 . Here is my code

DE:=diff(1/r(phi),phi,phi)+(1/r(phi))=(G*M/h^2)+(3*G*M/c^2*r(phi)^2));

ics:=r(0)=2/3,D(r)(0)=0;G:=1;M:=1;h:=1;c:=1;

p:=dsolve({DE,ics},numeric,events=[[r(phi),r(phi),halt]],[diff(r(phi),phi)=0,halt]]);

The code only works for the second event so it halts for r(phi)=1.63... etc

How do i stop this?

Thanks for any help.

How do I format the following dsolve function from...

December 05 2013
1 2

The differential equation I'm solving for is:

Solving of 4 differential equations simulateously...

November 18 2013
0 2

Hi everyone,

I am a new user of maple and i want to know the procedures to follow when solving 4 differential equations simultaneously.

e.g

ds/dt=Λ0-βcSI/N-μS

dL/dt=Λ1+βcSI/N-μ1L+ΑcIT/N

dI/dt=kL-μ2I

dT/dt=r1L+r2I-ΑcIT/N-μT

Any help will be highly appreciated. Regards

Solving ODE system with initial conditions...

November 10 2013
1 4

Hello all,

During my last attempt to solve ODE system (autonomous system which includes 3 first order diff. equations) with initial conditions, Maple had performed the solution which includes d_z1 parameter as follows below (I present the solution of one of the equations):

S(t)=S(0)∫(QN_z1+A)d_z1, where integral ∫ is defined integral from 0 to t, S(0) is the initial value of S, Q, N and A are the parameters. I would like to ask, what does it mean _z1 and d_z1? Why if the ODE system is only time dependent, I received the integral with other differential, that is d_z1? Does it mean that the integral can't be evaluated or maybe something else?

Thanks in advance,

Dmitry

2nd Order differential equation...

November 09 2013
1 4

Hey all new to Maplesoft my question is this;

how to do diff commands in Maple?...

November 02 2013
0 1

2. Give the Maple command(s) to compute \frac{\partial^8 f}{\partial^5 x \partial^3 y} for f(x, y) = e^{2x+ cos(y)}.

how to get kalman form...

October 18 2013
1 0

The goal is to get Kalman Form

https://docs.google.com/file/d/0Bxs_ao6uuBDUT25BeVhtWjZwRUU/edit?usp=sharing

https://docs.google.com/file/d/0Bxs_ao6uuBDUVXU5dXh6Rl9zUUU/edit?usp=sharing

I am doing the example in page 707 of Partial Differential control theory Volume 2 by J.F.

when using Robertz Daniel's Ore and Involutive packages

with(Involutive):

with(OreModules):

Alg := DefineOreAlgebra(diff=[D,t...

 1 2 3 4 5 6 Page 2 of 6
﻿