I have a set of 2nd order nonlinear differential equations which I solve numerically. 

odeplot plots the numeric results of the function and first derivatives just fine.

I was wondering if there is anyway to plot second derivatives.

odeplot treats a 2nd derivative as zero.

Although, I don't know  for sure, I believe the RKF45 routine computes them during the integration. Any way to store them?

Any ideas are appreciated.

Thanks

I have two differrential equations:

1) x ' ( t ) = x( t ) + y( t )

which can be written as

x ( t ) - x (t -1) = x ( t) + y (t )

- x (t -1) = x ( t) + y (t ) - x ( t )

- x (t -1) =  y (t )           A

2) y ' ( t ) = 4 * x( t )  + y (t )

which can be written as

y( t ) - y (t -1) = 4 * x( t )  + y (t )

y( t ) = 4 * x( t )  + y (t ) +  y (t -1)        B

Hi there.
I've been having difficulties figuring out how to make Maple update my plots when I use for example the scale axes tool, so it doesn't just stay at a default range of [-10;10] but instead updates to fill out the whole screen.

Hello,

First of all I would like to thank Joe Riel and congratulate him for the great maplev mode for emacs.
If any of you use it I would appreciate a little help with running "mint" from emacs.

Here's what the maplev specific part of my .emacs looks like,

When I want to simulate and plot the distribution from a random coin toss (normal distribution) I use the following code:

restart:
randomize():
coin:=rand(0..1):
coin_1:=proc(n) seq(coin(),i=1..n) end:
x_1:=seq([coin_1(10)],i=1..500):
x_2:=[seq(numboccur(1,x_1[i]),i=1..500)]:
with(Statistics):
Histogram(x_2,frequencyscale=relative,discrete = true );

what code should I use in order to get a coin with serial correlation. A normal distribution with fat tails? (Prefereably I want to tweak the above code)

Due to a do... for cycle I obtain thes data:

....

Dear all,

Does anyone know how to extend CodeGeneration[C], using AddFunction, so that the new function's signature matches a specific type of Matrix/Vector/Array?

By specific type I mean a match for a specific combination of indexing function, hardware datatype, order, and storage.

I haven't even had success using the 'anything' type in the signature, for (C) array arguments, for examples with the new function used within a proc and not just as an inlined example.

First the new function's "definition",

Hi,

eq1:=(3+Pi)*x^2*sin(x^2)

Is there a way to select then remove the x^2 alone but not in the sin( )

Mario

Ok, i am trying to plot the function abs(H)^(1/2) * sign(H). This function should be negative when H is negative, but for some reason the " * sign(H) " is having no effect on the plot, the plot is an even positive function rather than an odd function as it should be.

When I manually evaluate this function with a negative H using maple, a negative value is given back to me, however not in the plot... why is this.

Hello,

I'm new to Maple and am having some difficulty with solving a system of non-linear equations. Here are the equations:

Mt=M+K1*M*I+K2*M*I^2+K3*M*Z

It=I+K1*M*I+K2*M*I^2

Zt=Z+K3*M*Z

The values of Mt, It, K1, and K2 are known. I have a set of experimental values for Zt, and I can put in an initial guess of K3.

I need to determine a value of K3 that will satisfy the follwing: Acalc-Aobs=0, where Acalc=650*I+36800*K1*M*I+51000*K2*M*I^2.

Hi,

I'm using the solve commando to solve the next equation :

_EnvAllSolutions:=true:

solutions:=solve({2*x+3*lambda*x^2, 2*y+3*lambda*y^2, 2*z+3*lambda*z^2,g},[x,y,z,lambda]);

It's giving me a lot of solutions, but only a few are Real, most are complex and are not of use for the subject. I'd like to filter so it only gives the Real solutions. Already tried the package with(RealDomain)...but then it doesn't return any solutions.Also tried some assumptions yet, but didn't change anything.

Any hints whether this is possible or not?

Thanks.

Is there a quick way to remove a value corresponding to a given row and column position from within a table?

For example, say I wanted the result written out for the 4th column, 3rd row, and all I'd have to do would be enter say row:=3;  column:= 4; and have the data written out.  I've done something before like this in Excel with an IF command, but I can't get it working in Maple.

How can I export data that recieved from plot to external file