I'm solving a system of ordinary differential equations numerically, I used the dsolve(system,numeric) to do it. I have also plotted the solutions. Now I want to know where does this solution cross zero and use this value for later computations, is there a way to do it? 

This question is, as I think, equivalent to how to find the roots for a curve expressed in numerical arrays.

Thank you!

How to determine the volume of a sphere from its cross-sectional area, if we rotate it with center the diameter?

Gracias

I'm having trouble with the function G:=(n)-> 3 +2n-sum(sum(f(h), a=1..floor(m/2)), m=1..n) with base case G(0):=3, where h:=2a and f(h):=sum('f(2m)*3m, m=1..(h/2 -1).

For G(1), G(2) etc I get "Error, (in type/satisfies) too many levels of recursion" , note f(h) works properly. So I think the error is from the double summation. Any ideas what may be the problem?

Any help would be greatly appreciated.

Hello

I was trying to place the legend of a plot inside of it, and skimming through this site I found a solution based on a textplot, something like this:

plot(loglogplot1, loglogplot2, loglogplot3, loglogplot4): #just the functions to plot

textplot({[placement, 'typeset'(beta=10^-9 ),color=black],[...],[...],[...]}): #just the value of beta changes

plot([placement],x=4..6,color=[black,blue,red,green],linestyle=[solid,dash,dot,dashdot]):

Hi comrades. I am trying to do something like this
plot3d( fsolve( x^2 + a*x + b =0, x), a=0.1..5, b=0.5..3);
(this is not what I'm actually doing, I want to make a 3D plot of a more complicated function that uses fsolve, so don't just suggest the quadratic formula!).

I.e. plot the root of an equation as a function of some parameters in the equation.

It's not plotting because it says
"Error, (in fsolve) {a, b} are in the equation, and are not solved for"

Hello,

I have the following problem:

My function is defined by the determinant of 2 Heun functions

If I plot the phase I get something which looks quite what I'm looking for.

To get a better result I thought I would manually carry out the Wronskian as far as possible...

Doing some manipulations I get another form of the Wronskian which in fact should give the same result...

the problem is it doesnt :-(

I've added the spreadsheet....

In the solution set linked to above, I would like to replace each instance of the constant with ω. I feel that this should be possible with algsubs, but cannot figure out the proper...

Hello,

I am facing the error message "Error, (in factors) Bad inputs to diophant." raised by a call to

factors(p, {I, sqrt(3)}) 

for a polynomial p in 7 variables (with integer coefficients). Unfortunately, the error is not reproducible: After some thousand calls to factors (with different polynomials) this error suddenly occurs.

1. Interestingly, it does not depend on the actual polynomial,...

I know how to solve system of differential equations numerically, but now I want to know how to set a bound on the solutions. 

For example, if my system of DE is like this:   dx/dt = x+y   dy/dt = x-y    , solve x and y in t. 

I can solve this without any restriction on x and y, now I need to know how to bound x and y, e.g. x can only fall in the interval [0,1]

Thank you very much!

Hi, I am trying to do the calculation with a matrix, and I have hard time to find a way to calculate the Moore-Penrose generalized inverse of a matrix in Maple. Could anybody help me?

I have a solution with RootOF(_Z^6+....). I do not need to find the roots explicitly(I know that I should use 'allvalues' to find the roots). My question is "Is it okay if I use RootOF(...) expression in another equation without finding the roots explicitly? I mean does RootOF(_Z^6+...) stand for all its roots and can it be used for each roots?"

Thank you in advance.

Anybody has a hint on how to solve a non-linear system with trigonometrics. I want to solve x, y and z.

How can I use factor in equations?

For example:

x^6+y*x^4+z*x^2-g*x^4-3*x^6====>-2*x^6+(y-g)*x^4+z*x^2

or

a*cn+w*dn+e*cn+f*dn=====>(a+e)*cn+(w+f)*dn

These examples are very simple.

Thank you

How do you graph y''+8y'-9y=0?

How do you graph 4y"-y=0?

And for these i need to sketh the graph of the solution solution and describe its behavior as t increases.

with Maple?