## nonlinear differential equation...

hello my friends

I have a critical problem to solve below the system of differential equations

-(9/14)*R(t)^(19/14)-(285/196)*(diff(R(t), t, t))/R(t)^(9/14)+(2565/2744)*(diff(R(t), t))^2/R(t)^(23/14) = -k*(4*lambda+1/a(t)^3)

and R(t) = 6*((diff(a(t), t))^2/a(t)^2+(diff(a(t), `\$`(t, 2)))/a(t))

I need to find form of a(t) numerically from set of differential equatios

plz help me as soon as possible

## ¿How I change the output function to my ODE or PDE...

This is an example, the program gave me functions _F as outputs and i want to see what F is.

This is an example.

Thanks.

## How to use a NULL result from fsolve as a conditio...

Hi, I am using fsolve to find the roots x of a nonpolynomial expression f(x,a) = 0, using a loop for do to vary the values of the parameter a in small identical steps. At some stage, fsolve cannot find a solution. According to the Maple help, in this case fsolve returns a NULL sequence. I would like to know how to use the fact that fsolve cannot find a solution to break the loop with an if-then statement.

## How do I resize a displayed array of 3d plots in M...

Dear all,

In Maple 18, I type the following three lines and I wonder how I can then resize the resulting displayed window:

with(plots):
p1:=plot3d(x*y,x=-1..1,y=-1..1):
display(Array([p1]))

Any idea?

## Newton-Cotes procedure to evaluate coefficients...

Hi all, since I cannot use Latex over here I try to formulate as good as possible. Suppose we have the standard integral from a to b of a function f(x), which is equal to:

h * sum (k=1 to N) [ck f(a+kh)] +O(hp), where h=(b-a)/N+1, an p(N)>= N+1;

Would it be possible to write a procedure to evaluate the coefficients ck , k=1,2,3..N and P(N)

Perhaps a stupid question, because I don't know if it is possible.

Best wishes, Math

## How do i solve first order differential equation w...

Hello,

I am a beginner with Maple. I had some basic tutorials. In fact I want to solve a first order differential equation with non-constant coefficient:

Can you really tell me what are the steps to follow in Maple 18 in order to solve this equation. I didn't find any tutorial or work that deals with variable coefficients.

## Balance of a body with learning sequence with...

Maple 18

Using the learning sequence as an alternative to learn problems related to "balance of a body" is shown in this video; thanks to the kindness that Maple offers us in its fundamental programming syntax.

Balance_of_a_body_with_learning_sequence.mw

Lenin Araujo

## length of 2 dimensional array with variable length...

I have a 2 dimensional array with variable length. I want to extract the number of elements of each row. For example What is the number of element in x(1,i)?

## Field plot problem. ...

Hi everyone, I am trying to plot field lines but I face problem in plotting field plot. kindly help me if anyone can do it. Find the code in the attached file. Thank you.

Field_lines.mw

## I have problem with the code....

Hi, i want to investigate  chaos for the problem , cantilever beam under random narro band excitation, but the code has errors .the code is this:

restart:with(plots):      h:=1: Omega:=(0..376):alpha1:=617.2:alpha2:=1.02*10^(8): c:=.002:k:=18.4:  step:=0.1:imax:=376:  for i from 0 to imax do;  Omega[i]:=i*step:   f:=evalf(solve({((-a*Omega[i]^(2)+alpha1*a+3/(4)*alpha2*a^(3)+1/(4)*k*Omega[i]^(2)*a^(3)-(3)/(4)*k*Omega[i]^(2)*a^(3))^(2)+(c*Omega[i]*a^())^(2))=h^(2),a>0}));  ff[i]:=((rhs(f[1]))^(2))/(2):  end do:   l1:=[[Omega[n],ff[n]] \$n=0..imax]:  p1:=plot(l1, x=0..3,y=0..1,  style=point,symbol=solidcircle,symbolsize=4,color=red):    jmax:=914: f1:=array(377..914):f2:=array(377..914):f3:=array(377..914):Omega1:=array(377..914):  for j from 377to jmax do;  Omega1[j]:=j*step:   fff:=evalf(solve({((-a*Omega1[j]^(2)+alpha1*a+3/(4)*alpha2*a^(3)+1/(4)*k*Omega1[j]^(2)*a^(3)-(3)/(4)*k*Omega1[j]^(2)*a^(3))^(2)+(c*Omega1[j]*a^())^(2))=h^(2),a>0}));  f1[j]:=((rhs(fff[1,1]))^(2))/(2):f2[j]:=((rhs(fff[2,1]))^(2))/(2):f3[j]:=((rhs(fff[3,1]))^(2))/(2):  end do:   ll1:=[[Omega1[n],f1[n]] \$n=377..jmax]:  pp1:=plot(ll1, x=0..10,y=0..1,  style=point,symbol=solidcircle,symbolsize=4,color=red):    ll2:=[[Omega1[n],f2[n]] \$n=377..jmax]:  pp2:=plot(ll2, x=0..10,y=0..1,  style=point,symbol=solidcircle,symbolsize=4,color=red):    ll3:=[[Omega1[n],f3[n]] \$n=377..jmax]:  pp3:=plot(ll3, x=0..15,y=0..1,  style=point,symbol=solidcircle,symbolsize=4,color=red):       plot({  seq(seq(p1), seq(seq(pp1),seq(seq(pp2),seq(seq(pp3))  },style=point,title=`Pitchfork Diagram`);  Thanks for your help

## Problem simplifying complex expresions....

Dear all,
When I try to simplify the expresion z+conjugate(z) I get, as expected, 2*Re(z).

The problem arises when I try to do the same with a more complicated expression as z1*conjugate(z2)+conjugate(z1)*z2. Trying to simplify this Maple only give me back the expression with nochange. The expresion is equivalent to the first example so I expected to get 2Re(z1*conjugate(z2)).

Does anybody know how to solve this problem?

## How to change the position of Label in 2-D plots?...

Dear All

Is it possible to change the position of labels so that they do not overlap with curves of plots? Please see the attached file in which I want to shift label for vertical axes to slightly left and label for horizontal axes to the slightly right.

Plot_Label.mw

## Why PolyhedralSets package could not work in Mapl...

Hi Dears,

I installed Maple 15 and 18 on my PC. But, when I want to use the PolyhedralSets package the following error is appeared. Is this package only on Maple 2015?

With the bests.