# Items tagged with differentialdifferential Tagged Items Feed

### DEs and Mathematical Functions Updates...

May 06 2014
2 0

This is the first presentation of updates for the DE and Mathematical Functions programs of Maple 18. It includes several improvements, all in the Mathematical Functions sector, as well as some fixes. The update and instructions for its installation are available on the Maplesoft R&D webpage for DEs and mathematical functions. Some of the items below were mentioned here in Mapleprimes - you are welcome to present suggestions or issues; if possible they will be addressed right away in the next update.

• Filling gaps in the FunctionAdvisor regarding all the 6 complex components: abs, argument, conjugate, Im, Re, signum, as well as regarding Heaviside (step function), Dirac, min and max.
• Fix the simplification and differentation rule for doublefactorial
• Make convert(..., hypergeometric) work the same way as convert(blabla, hypergeom)
• Implement integral forms for Heaviside(z) and JacobiAM(z, k) via convert(..., Int)
• Implement appropriate display for the inert %intat function as well as its conversion to the inert Int
• Make the FunctionAdvisor/DE return not just the PDE system satisfied by f(z, k) = JacobiAM(z, k)and also (new) the ODE satisfied by f(z) = JacobiAM(z, k)
• Fix conversion rule from Heaviside(z) to Sum
• Fix unexpected error interruption when differentiating min(...) and max(...) containing more than three arguments
• Fix issue in simplify/conjugate
• Improvement in expand/int: factors in disguise are put outside the integration sign
• Various improvements in the case of multiple integrals involving the Dirac function
• Make Intat fully inert (before it was evaluating its arguments)
• Make value of inert indexed objects work

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

### 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

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.

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？

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

### 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?

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)}.

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