a curve has residual p if it is linked, in a complete intersection, to a curve with residual p-1

0 residual if is a complete intersection of two surfaces

do complete intersection means two surfaces totally overlapped?

why they are not the same one if complete intersection?

how to test whether a curve  lies in no plane in maple?

Hello,

I am trying to make c (0.001<=c<=0.02) a random value at each time step.But with my code c is choosing randomly from the interval then solveing the equation for fixed c at each time step.

How can I mack c a diffrent random value at each time step?

This is my code:

> with(DEtools); with(plots);
>
> Ra := RandomTools:-Generate(distribution(Uniform(0.001, 0.02))); c := Ra;
> f := .1;
>
> eq := diff(X(t), t) = 1-f-c*X(t);
>
> init := X(0) = 100;
>
> sol := dsolve({eq, init}, {X(t)}, range = 0 .. 100, numeric);
>
> odeplot(sol, [[t, X(t)]], t = 0 .. 100);

Thank you

I have a rather complex expression that I want to find the zero for as a function of two other parameters, i.e. I have a function

Denom := (s,M,g) -> stuff

that I want to find the zero of for a variety of values of M and g. In some cases the solution will be complex, which is entirely acceptable. However, the real part of the solution should never be negative, and yet that is the kind of result I am getting.

As an example (illustrated in the worksheet, when attempting to find the zero for M = 3 and g = 0.2, fsolve gives me s = -6.1 -1.4i. However, when I plot the function with the parameters input already, I can clearly see a zero at s = 9 with no imaginary component. Why won't fsolve find this zero? How can I make it do so?

See the bottom of the attached worksheet for the main problem.

 pole-dragging-mapleprimes.mw

test.mw

In this file, I tried my best to solve the pde. But the answer is still rather non-informative. I need some help to simplify it.

I did notice that my Maple might need reinstallation, due to a "bug" in the 18.02 update.

My ultimate aim is try to use some similar techniques to solve this, test2.mw, which has a similar type pde.

The standard pdsolve(pde) would just not work.

UPDATE:

I used the same file in Maple 17 on a differnt Machine, which can be solved by pdsolve. So I guess it's just that  the 18.02 update package is broken itself. I have tried to uninstall and reinstall twice.

Thanks,

casper

Hi all,

I'm currently writing a code to solve the equations for a gravitational collapse of a star numerically. I'm using two dimensional Arrays for most of the physical quantities in my finite difference equations, with one index for the spatial dimension (I'm only considering spherically symmetric collapses) and one time index. I wrote two nested loops, where the inner one solves the equations from the centre of the star to the surface (with the exception of one quantitiy, where I have to integrate the other way around) and the outer loop advances the Arrays in time. My problem is, that Maple doesn't seems to evaluate the two dimensional Arrays. Instead for inserting the appropriate value for e.g. A[3,2], Maple just keeps on using A[3,2] which messes up some formulas, since I have to take roots of the numbers. At least that is what seems to be going on when I'm trying to debug the relevant part of the code and I check for the values, with whicih Maple calculates. I'm also using a one dimensional Array to store the timesteps, I'm using in the code and Maple doesn't seem to have problems evaluating them. Is anybody familiar with this problem? Does Maple have trouble with multidimensional Arrays in loops or have I just messed up my code? I have uploaded my code (I hope it worked). I apologize for my code being messy, but it's the first time I'm working with Maple and using numerical methods. The part which troubles me is labeled "# actual code".

Thank you all.

Oppenheimer-Snyder_Maple_3.mw

I was trying to see if Maple contains equivalent to Mathematica FreeQ command to check inside a proc if an input expression contains an "x" or not.  I could not find such command in Maple. So now I call indets(), which is a nice function, that tells me all the symbols in the expression, then use member() to check.

Would this be correct way to do this? Here is an example

expr:=3+4*sqrt(2)-x+y*sin(3*t);
s:=indets(expr);
if member(x,s) then
   print(`yes, x is there`);
fi;

I can't use patmatch() for this, as I do not know what the expression will look like yet, I just needed to know if it contains an "x" (in this case), a free symbol "x", and that is all.

I thought to ask if there is a better way to do this.

Hello People in Mapleprimes,

I have a question about the codes in the help page of assign.

Please tell me about this.

The folliowing codes were written there:

code (A)

assign(a,c):

assign(a=d,b=2):

a,b,c;

The output of these was 

d,2,d

I think that assign(a,c) means assign(a=c) or a:=c, not c:=a.

If what I wrote was true, the output of the above code should be

d,2,c.

And, if I changed assign(a,c) to assign(c,a), the output was d,2,d, which is the output written on the helppage 

of the assign. On the other hand, the output of code A was surely d,2,d.

Why does assign(a,c) have the same meaning as assign(c,a)?

Best wishes

taro

Hello everyone, I am having problem while trying to evaluate the double integral written in the file attached double_inegral.mw. Please help me out.
Many thanks in advance.

I am getting different results when determining the eigenvectors of a simple beam vibration problem in 2 ways :

See attachment :
1) When generating a matrix with GenerateMatrix([eqs..],[A,B...]) , or with
2) reformulating the same matrix by hand with S:=Matrix(4,4,[[ ]]) I get different eigenvectors for actually the same matrices ?

Tried already commands like 'convert' , 'Normalize', setting precision, to no avail.
Is this due to rounding ?

Any suggestions ?

Thanks ! 

Eigenvectors_2.mw

The link to the .mw file is underneath the content.

I was trying to solve the first order ode for x(t). pp1 and pp2 are essentially diff(x(t),t).

I just wanted to see them plottet. While deriving these equations (which stem from a first order nonlinear quadratic diff. eq.) I had to distinguish between those 2 solutions. Also I made the assumption that diff(x(t),t) everywhere so the only solution being allowed should be pp1. Oddly the analytic solution for pp2 looks like the numeric solution for pp1 and my question is: Why is that?

Download rutschender_Stab.mwrutschender_Stab.mw

Hi there,

How can I plot the equation $r=1/theta$ in polar plot in maple13? and in general for plotting $r=1/(theta-alpha)$ alpha is constant.?

 Any help will be appreciated.

Regards

Yegan

Hi

equation:

X=1/(a)*[2/(mc0^(m-2)]^(1/2)*(c/c0)^(1-m)*[(c/c0)^m-1]^(1/2)*F(1,1-1/m;3/2;1-(c/c0)^(-m))

for:

c0=0,0.277164,0.340257,0.408617,0.581345,0.649268 and a^2=2

and   m=0,1/2,1/3,3/4,2,3

if 0<x<1 and 0<C(x)<1

and F is hypergeometric function

plot C(x) vs. x

I tried to run a few calculation on maple, the numerical output is, e.g.

0.3 10^(-5)

Is there any simple way to set it as 0.3e-5? I am not intened to write the data into a file, hence, i am not sure if writedata is a suitable option.

Thank you very much! 

Hello people in Mapleprimes,

I want to do calculations about an expected value.

For example,

expectedvalueofc.pdf

that is, \int_a^b c d \Omega

where, \Omega is a distribution function of c. 

But, I don't know whether this equation can be put into worksheet.

Is there no way other than writing this as 

\int_a^b c g(c) dc, 

where g shows a probability density function.

Can I use Statistics[ExpectedValue] to calculate expected value with a general distribution function, not specified 

to normal distribution?

I hope you will give me some hints.

Best wishes.