Below are five subsindets commands.

I believe I understand the actions of B and C, but I fail to understand the actions, individually and taken together, of  E, F and G.

B := subsindets(u(i, j)^2*v(i, j)+u(i-1, j), 'specfunc(u)', proc (f) options operator, arrow; subsop(1 = op(1, f)+1, f) end proc);

C := subsindets(u(i, j)^2*v(i, j)+u(i-1, j), 'specfunc(anything, u)', proc (f) options operator, arrow; subsop(1 = op(1, f)+1, f) end proc);

E := subsindets(u(i, j)^2*v(i, j)+u(i-1, j), 'specfunc(symbol, u)', proc (f) options operator, arrow; subsop(1 = op(1, f)+1, f) end proc);

F := subsindets(u(i, j)^2*v(i, j)+u(i-1, j), 'specfunc(`+`, u)', proc (f) options operator, arrow; subsop(1 = op(1, f)+1, f) end proc);

G := subsindets(u(i, j)^2*v(i, j)+u(i-1, j), 'specfunc({`+`, symbol}, u)', proc (f) options operator, arrow; subsop(1 = op(1, f)+1, f) end proc);

Where can I find a thorough explanation of specfunc with examples?

I have learned that the eigenvectors of an solid object's Inertial Tensor are its principal axes and are an orthonormal set, however two of the eigenvectors in the cube in the uploaded worksheet are not orthogonal.

Where is my error?

CubePrincipalAxes.mw

A catenoid is the minimal surface between two 3D circles which are co-axial and parallel.

Is there a technique for finding the formula for the minimal surface if the circles are "stretched" into ellipses with proportional major and minor axes?

In the application whose link is below, an error message results when I right click the fsolve command and select explore.

https://www.maplesoft.com/applications/view.aspx?SID=119851

I would like to explore changes to several of the parameters in the equations named "sys", especially the value of Qoutflow. Can this be done and, If so, how can the solved values, Q1, Q2, Q3, and H be graphed as the slider values of individual parameters values are modified?

I would like to find which of my approximately 150 recorded worksheets reference the VariationalCalculus package.

Instead of tediously displaying these one at a time, is there a search mechanism that will list the names of all my worksheets containing the command with(VariationalCalculus)?