hi, i am trying to solve a PDE f(x,z,t) with mixed boundary conditions, while Maple just gives u(x,z,t)=0 which is incorrect, so i believe somewhere must be wrong, someone has an idea?  

Governing equation: ,    0<x<M, 0<z<L, t>0

IC: heat source is a point at (0, z0):  u(x,z,0)=c*dirac(x-0)*dirac(z-z0) , where c is a temperature at t=0.

boundarys of domain are cauchy boundaries: du(0,z,t)/dx=0;  du(M,z,t)/dx=0; du(x,0,t)/dz=0;  du(x,L,t)/dz=0

the code is: 

PDE := diff(u(x, z, t), t) = a*(diff(u(x, z, t), x, x))+b*(diff(u(x, z, t), z, z));
IBC := u(x, z, 0) = c*Dirac(x-0)*Dirac(z-z0), (D[1](u))(0, z, t) = 0, (D[1](u))(M, z, t) = 0, (D[2](u))(x, 0, t) = 0, (D[2](u))(x, L, t) = 0;

pdsolve([PDE, IBC], u(x, z, t)) assuming 0<x<M, 0<z<L

thanks in advance!! 

Hi, 

I was able to determine a cubic spline fit, F(v), to x1 and y1. Now I have vector x2 which I would like to use F(v) to calculate y2 as another Vector[row]. I am having trouble accomplishing this task. Any help is greatly appreciated. Thanks.
 

Download splfit.mw

I have a similar matrix.

Build through matrixplot, not exactly what I need to get. I need a way to plot without zero values on the graph.
 

how to compute example 1 of linear schrodinger equation?

[Edit: uploaded .pdf file of M.M. Mousa and S.F. Ragab, Z. Naturforsch. 63a, 140 – 144 (2008) removed for copyright reasons]

I am trying to get the function of the curve in this picture. But, I don't know how to start. How can I get function of the graph in this picture?
I guess f(x) = (x + 1) (x - 1) (x - 3), if -1 <= x <=3.5 and f(x) = -(x + 1) (x + 2.5), if -2.5 <=x <=-1.

In Maple 2018, I was playing around with some sums of infinite series, and I came across a result that made me wonder if Maple was perhaps using some other definition or understanding of the sum of a series in its calculation. Take a look at the screenshot linked below:

https://ibb.co/hMdkQHn

That first series is most certainly divergent since the limit as n approaches infinity of n^2/(n+1) is not equal to 0. And just to confirm my own sanity, I even checked some of the partial sums of the series, which sure enough are diverging. And yet for the infinite sum, Maple is giving this finite result.

I even checked a more familiar alternating series, the alternating harmonic series, which Maple does correctly calculate to be ln(2).

What am I missing here? Is Maple using a different definition for the sum of the series than the limit of the partial sums as n approaches infinity? Or is there a mistake with how I've written something that I'm not noticing?

Dear Users,

I am solving a large system of linear equation with the Hybrid solver. Up to 2400 equations, I get a solution, but if I change the number of equations to 3000, I don't get any solution in fact solution entry reads Float(undefined). All the entries in matrix and vector are floating point decimal with 32 digits of accuracy. Any idea how to overcome this?

thanks.

i attach my file

maple_pita_he.mw

Suppose I have

solution:=fsolve(f(x,y)=0,x,y)

this returns 

x=<result>, y=<result>

I want to continue the computation in my worksheet by assigning values to x and y without copying the numerical values by hand.

x:=<result>

y:=<result>

Then I want to make more computations with x and y.

It is too time consuming to copy the numbers by hand each time I run the worksheet

Larry

And y

the principle is so easy as the method for demonstration of area of a disk by dissecting it to tiny sectors ...

and i just reversed the topic and i formed a shape by rearranging the tiny triangles that made the area of point and straight line as you can see in graph or interactively download the maple 18 worksheet that i attached ...

BUT my problem is that i can't yet underastand what is the formula or equation of this curve ?

the only obvious prperties of the curve is its ARC LENGTH that must be the half of straight line !
SO I NEED THE HELP OF PROFESSIONALs ?

also the programming and impelmenting of this subject in maple language was so hard for me !!!

I hope mapleprimes employee or developers offer more efficent and intelgent algorithm for using Maple in such cases ...

unknown_curve_by_shekofte.mw
 

Download unknown_curve_by_shekofte.mw

Download solve_equattion.mw

hi

in every math software there is a page which we could find our results in tabels  as numerical output ..is there like this in maple?

Hello guys, I want to compute Einstein tensor components of Kerr metric, but it seems there are some problems with computing.

Thank you for your help.Kerr.mw

Greetings,

How se the f^(IV) ode problem using the Runge metho. 

restart; with(plots);
fcns := {f(eta), gta), t(a)};
N1k1 ;b :; nt 3; pr := 5; sc := 1;
eq1 := diff(f(eta), `$`(eta, 3))+(1/2)*f(eta)*(diff(f(eta), `$`(eta, 2)))+k1*((diff(f(eta), `$`(eta, 1)))*(diff(f(eta), `$`(eta, 3)))-(1/2)*f(eta)*(diff(f(eta), `$`(eta, 4)))+(1/2)*(diff(f(eta), `$`(eta, 2)))^2) = 0; eq2 := diff(t(eta), `$`(eta, 2))+pr*nb*if`ta, 1)))*(diff(g(et`$`(eta, 1)))+pr*nt*(diff(t(eta), `$`(eta, 1^2+(1/2)*f(eta)*(diff(t(eta), `$`(eta, 1))) = 0; eq3 := diff(g(eta), `$`(eta, 2))+nt*(diff(t(eta), `$`(eta, 2)))/nb+(1/2)*f(eta)*(diff(g(eta), `$`(eta, 1)))*sc/pr = 0;
bc := f(0) = 0, (D(f))(0) = 0, (D(f))(N) = 1, ((D@@2)(f))(N) = 0, t(0) = 1, t(N) = 0, g(0) = 1, g(N) = 0;
R := dsolve(eval({bc, eq1, eq2, eq3}), fcns, type = numeric);
Error, (in dsolve/numeric/bvp) system is singular at left endpoint, use midpoint method instead
p1u := odeplot(R, [eta, (D(f))(eta)], 0 .. N, numpoints = 100, labels = ["&eta;", "f'"], linestyle = solid, color = [blue], thickness = 1, labeldirections = [horizontal, vertical], labelfont = ['TIMES', 'BOLDOBLIQUE', 16]);
Error, (in plots/odeplot) input is not a valid dsolve/numeric solution
p1u;


bvp.mw

Have a good day.

simplify_question.mws
Am trying to teach myself about lines and circles and inversion.  In the code below I'd like to put textt on the circles eg c1 to identify circle c1 etc.I'm more familiar with the textplot command & plottools, but want to use the draw command.  I've tried some options with the circle statement without success.
circle(c1,x^2+(y-2*R*cos(Pi/6))^2=R^2):  # 'ctext'=c1):

Is it possible to position text in a draw statement, similar to the textplot statement (that uses plot)?  

  I was amused by an idiosincracy of Maple 7.  The last line of my code uses the simplify command, yet I have had to resort to the simplification myself - (on the previous lines).   I was surprised and curious about this.  The Help section on simplify mentions several high power simplification procedures, yet fails to simplify a simple expression.  Any comments on this?

   I'm interested in learning more about circle inversion and wondered if anyone knew of some elementary books on this.  Geometry Inversion was never taught to me at school, nor university, despite it being a topic over 1000 years old.

   Thanks for your time.  Any comments, answers, gladly appreciated.      

Download simplify_question.mws