I use D[ ] to get partial derivatives,

as follows,I donot know is it right?

w := proc (x, y) options operator, arrow; A*(x^4-2*L*x^3+L^3*x)*sin(n*y/R) end proc

t4 := (D[`$`(1, 4)](w))(x, y)+2*(D[`$`(1, 2), `$`(2, 2)](w))(x, y)+(D[`$`(2, 4)](w))(x, y)

I use the order linsolve to solve matrix,but it does nothing. It is as follows,

a := matrix([[-k, -c*omega], [c*omega, -k]])

b := matrix(2, 1, [A1, B1])

d := matrix([[M*omega^2-K-k, -c*omega], [c*omega, M*omega^2-K-k]])

f := matrix(2, 1, [A2, B2])

g := matrix(2, 1, [0, F])

h := matrix([[m*omega^2-k, -c*omega], [c*omega, m*omega^2-k]])

dbg1 := evalm(`&*`(d, b)+g)

AB2 := linsolve(a, dbg1)

In Maple, is there `Muller` order can be directly used?

  I have a function such as p := proc (x) options operator, arrow; x^5+11*x^4-21*x^3-10*x^2-21*x-5 end proc, somebody wrote the method as r1:=muller(p,-13,-12,-11,.000001,100,r1); but maybe it is wrong.

I want to know how to use the method-muller.

Thank you very much.

In the help, it writes

BesselJ and BesselY are the Bessel functions of the first and second kinds, respectively. They satisfy Bessel's equation:
     2                2    2
    x  y'' + x y' + (x  - v ) y = 0
 

I want  to calculate the derivative of Bessel, I do