I define the spherical Bessel function with j([n, z]) := sqrt(2)*sqrt(Pi/z)*BesselJ(n + 1/2, z)/2.  Then I attempt to plot with

Digits := 20;
plot(j([1, z]), z = 0 .. 25);

I get an empty plot and an error message: 

Warning, expecting only range variable z in expression j([1, z]) to be plotted but found name j

which makes no sense to me.

(I am using Maple 2019.)

Hi

I would like to solve the non-linear system to obtain rho1 and rho2 .

But when i use solve i get the following error
Error, (in solve) cannot solve for an unknown function with other operations in its arguments

system.mw

many thanks

>SIRvector := [op(SIRvector), op(evalf(solve(eval({Yeqnx(1), Yeqny(1), Yeqnz(1)}, SIRvector), {JJ(1), RR(1), SS(1)})))];

I have a picture. I tried to find the formula of the curve
My code

t := proc (x) options operator, arrow; b*x^10+c*x^9+d*x^8+e*x^7+f*x^6+g*x^5+h*x^4+i*x^3+j*x^2+k*x+l end proc

And solve
solve([t(-2) = 2, t(0) = -2, t(1) = 0, t(2.5) = -3, t(3.5) = 0, t(-1) = 0, eval(diff(t(x), x), x = -2) = 0, eval(diff(t(x), x), x = 0) = 0, eval(diff(t(x), x), x = 2.5) = 0, eval(diff(t(x), x), x = 1) = 0, t(2.8) = 0], [b, c, d, e, f, g, h, i, j, k, l])

[[b = -0.2688965311e-1, c = .1687428810, d = -0.3166922031e-1, e = -1.490599337, f = 1.885667707, g = 3.845330330, h = -6.939129440, i = -2.523473874, j = 7.112020606, k = 0., l = -2.]]

I ploted

plot(-.2688965311*x^10+.1687428810*x^9-.3166922031*x^8-1.490599337*x^7+1.885667707*x^6+3.845330330*x^5-6.939129440*x^4-2.523473874*x^3+7.112020606*x^2-2, x = -3.5 .. 4.5)

The result too far with picture. How can I repair?

I want to made a comparison via plots of RK-4, NSFD and LWM.

Restart

eqn1 := diff(x(t), t) = x(t)*(2-(1/20)*x(t))-x(t-tau)*y(t)/(x(t)+10)-10;

eqn2 := diff(y(t), t) = y(t)*(x(t)/(x(t)+10)-2/3);

bc := x(0) = 40, y(0) = 16,tau=0;

sol := dsolve({bc, eqn1, eqn2}, numeric);

plots[odeplot](sol, 0 .. 10);

I got the plot Vertically x and horizontally t but i need vertically y and horizontally x, Please help me, how can i write the code for ploting, thanks in advance.

I am trying to calculate the contour integral of exp(-z/A)/z^{2+n}, for constant A and integer n. Here is the Maple code (forgive me, very beginner Maple user here!):

restart;

f := exp(-z/A)/z^(2 + n);
                                 /  z\
                              exp|- -|
                                 \  A/
                         f := --------
                               (2 + n)
                              z       


op~([singular(f, z)]);
                            [z = 0]
poles := [0];
                          poles := [0]
C := z -> is(abs(z) < 1);
assume(2 <= n);
(2*Pi)*I*add(residue(f, z = a), a = select(C, poles));
                              /   /  z\       \
                              |exp|- -|       |
                              |   \  A/       |
                2 I Pi residue|--------, z = 0|
                              | (2 + n)       |
                              \z              /

You can do this by hand by simply expanding the exponential, but how do I make Maple actually do the calculation? (instead of just answering with "residue...".

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