Maple AM2 2FREQ

Cart2esf:= proc(x,y,z)
local R,theta,phi
R = sqrt(x^2+y^2+z^2)
if x ≠ 0 then theta = arctg(y/x)
  else if y = 0 then theta = 0
         else if y > 0 theta = pi/2
               else theta = pi/2
end if
if R = 0 then phi = 0
else
  phi = arccos(z/R)

Cilindricas2esfericas := (x,y,z)
Local x,y,z
R = sqrt(x^2+y^2)
if x ≠ 0 then theta = arctg(y/x)
  else if y = 0 then theta = 0
         else if y > 0 theta = pi/2
               else theta = pi/2
end if

Esf2cart:=(r,theta,phi)
local x,y,z
if evalf(r>=0,0<=theta<=2pi,0<=phi<=pi)
x = R*cos(theta) * sin(phi)
y = R*sin(theta) * sin(phi)
z = R*cos(phi)
return [x,y,z]
else error "Valores fora do dominio"
end it