MAPLE中的方程如下，代码可直接复制粘贴到程序中
如何调用极坐标系？？？？？
diff(u(r, theta), r, r)+(diff(u(r, theta), r))/r+(diff(u(r, theta), theta, theta))/r^2 = 0
边界条件：u(r, theta) = f(theta)
如何调用极坐标系？？？？？
diff(u(r, theta), r, r)+(diff(u(r, theta), r))/r+(diff(u(r, theta), theta, theta))/r^2 = 0
边界条件：u(r, theta) = f(theta)
