@Madhukesh J K There are two basic types of 3D plots, and they can be distinguished by the number of dimensions of independent variables (real values that you directly vary) and dependent variables (real values that are computed using the independent variables). So far, you have not given us a complete set with which to construct either type of plot. The two types are a space curve (1 independent variable, 3 dependent variables) and a surface (2 independent variables, 1 dependent variable).

Your Reply immediately above implies that you want 1 independent variable (phi2) and 2 dependent variables (skin friction and Nusselt). That's not one of the types of 3D plot that I discussed, although it's enough to make a 2D plot, a plane curve.

These are mathematical limitations, not limitations of Maple.

@Mac Dude I have the same problem. It has been there for years. I do not use a .bat file.

Currently, my := is lowercase d and my -> is numeral 1. One the problem infects one worksheet, it infects all open ones. The only solution I've found is to shut down and restart Maple entirely.

@Bohdan Like this:

MyA(1, 1, 2, 2, 2, 2, 2, gamma, beta, pi, alpha, epsilon):
diff(%, pi[1,2,1,2]);
 

@tomleslie The Question shows chi(eta) and its derivatives in eq4.

@9009134 You wrote:

• I think I need to plot the 2D gradient of V in-plane xz and xy, according to the relation between x,y,z, and tau and sigma.

I think that you need to plot in an alternate coordinate system. Maple knows many, or you can define your own.

@9009134 The problem was that you didn't remove the line V:= Gradient(V) like I said.

@Bohdan The problem is that you're using 2D input.

@a_simsim Your dsolve command should be

sol:= dsolve({odesys[], ics[]}, numeric, known= Q(t));

@Bohdan I only suggested Physics:-Library:-Add because it may be able to "pretty print" the summations with the inequalities at the bottom. Computing the formulas is straightforward with regular add, and shown below. If you do want to do that pretty printing, you should ask a separate Question. Here is your formula A:

MyA:= (
    i::posint, r::posint, j::posint, s::posint, F::posint,
    J::posint, S::posint,
    gamma::{name, table}, beta::{name, table}, pi::{name, table},
    alpha::{name, table}, epsilon::{name, table}
)->
local
    Jj:= {$1..J} minus {j},
    Omega:= zz->
        add(
            alpha[k,s]*pi[j,k,s,F]*
            `if`(nargs=0, add(pi[z,k,s,F], z= Jj), pi[zz,k,s,F])*
            add(gamma[k,u]*beta[k,u], u= 1..S)
            +
            add(
                gamma[k,s,u]*beta[k,u]*pi[j,k,s,u]*
                `if`(nargs=0, add(pi[z,k,s,u], z= Jj), pi[zz,k,s,u]),
                u= 1..S
            ),
            k= 1..J
       )
;
    epsilon[s]*gamma[i,r]/beta[j,s]*(
        Omega()*(pi[i,j,r,s]*gamma[j,r,s] + `if`(r=s, `if`(i=j, 1, -1), 0)) +
        add (pi[i,z,r,s]*gamma[z,r,s]*Omega(z), z= Jj)
    )
;     

Regarding the derivative of the formula: Do you mean when J, S, and the indices of the differentiation variable have specific integer values? If so, then plain diff will work.

Does that worksheet work for you? And, if so, what was the problem before?

@ecterrab I agree about the potential confusion caused by Maple's type algebraic, and so it would likely be best to avoid the word. (Although, I wish that that type name were changed! Type algebraic is much more general than the mathematical concepts algebraic numbers, algebraic functions, or algebraic equations (as in "system of differential-algebraic equations (DAEs)). That's never going to happen though.)

Regarding not versus non-: Not is an adverb, and in this case it modifies the verb can include. So, as it stands, the help-page phrase is equivalent to "can include ODEs and cannot include differential equations", and this is how nm understood it. To negate an adjective such as differential, use the prefix non-, which may also be attached without a hyphen.

I deleted a duplicate of this Question, whose only difference seemed to be different names of the variables. 

@janhardo A restart command should always be placed in its own execution group (its own prompt). While it usually doesn't cause problems if it's mixed with other commands, when it does, those problems are usually GUI related and difficult to predict. This is because the GUI and kernel run asynchronously. This is my first suspicion for the restart problem that you describe, but it's only a suspicion.

@nm The help-page phrase that you asked about, "...can include ODEs and not differential equations", should be "...may include ODEs or non-differential equations" or "...may include ODEs or algebraic equations". Does that clear up the confusion for you? And, if so, which of the two alternative rephrasings is clearest?

@9009134 Here it is:
 

Download GradPlot.mw