The error message in Maple 11 is Error, (in DEtools/DEplot/CheckDE) derivatives must be given explicitly Now if you look at the system of DE's you're giving to DEplot3d, it looks like this: diff(w(t),t) = (complicated function of t and w(t)), w(t) = diff(z(t),t), D(x)(t) = -sin(t), D(y)(t) = cos(t) but actually x(t) and y(t) have already been defined. The unknown functions in DEplot really need to be undefined, so change x to X and y to Y in the left sides of your equations and in the specification of variables. You'll also need initial conditions for X and Y. So try X(0) = 0, Y(0) = 0. Now you get a warning: cannot evaluate the solution past the initial point, problem may be complex, initially singular or improperly set up Examining the system at the initial conditions, I see that the right side of the first DE involves the square root of an expression that will be 0 at t=0. This could be bad news as far as differential equations are concerned, because the square root function is not Lipschitz at 0. It's not even certain that the solution is unique. If you change the initial condition to w(0) = 1.001 instead of w(0) = 1, DEplot3d does work, but you run into another apparent singularity (with w(t) blowing up) around t = .93724871.

Be sure to tell us the name of your instructor, so we can tell him/her how much we enjoyed helping you.

Be sure to tell us the name of your instructor, so we can tell him/her how much we enjoyed helping you.

It might help if you uploaded your file. At least we could take a look at it.

I think the posting you're referring to is this one: http://groups.google.ca/group/sci.math.symbolic/msg/209ad4ec4b128610

I think the posting you're referring to is this one: http://groups.google.ca/group/sci.math.symbolic/msg/209ad4ec4b128610

I'm assuming n is a given positive integer. The simplest way is > {seq(seq([i,j,n-i-j],j=0..n-i),i=0..n)}; Somewhat trickier, but not as efficient, would be > with(combinat): convert(map(op @ permute @ (t -> t - [1,1,1]), select(t -> (nops(t)=3), partition(n+3))),set);

It first makes an appearance in Maple 10, I think. I haven't encountered it in any documentation. I suspect it's a side-effect of something else.

The Oxford English Dictionary says: French martingale is attested earliest in the phrase chausses a la martingale hose that fasten at the back (1491); cf. Occitan braias à la martegala hose that fasten at the back, and Italian martingala (a1556; also 1598 in sense 1 [the horse-harness]), Spanish martingala (1529) in the same sense. The application may arise from a belief that the inhabitants of Martigues, a remote town, were eccentric and naive; hence also the application to an apparently foolish system of gambling. Sense 2 [the ship-rigging], however, is prob. attributable to the former importance of Martigues as a port and ship-building centre. Sense 1 is variously explained: some take as a development from the application to hose (although N.E.D. (1905) holds that the opposite is the case); Französisches Etymol. Wörterbuch takes this sense as developed from nautical uses, in spite of the chronology in English and French. A derivation of Middle French, French martingale from Spanish almártaga, almártiga kind of headstall put on horses over the bit to steady them when the rider dismounts (1500), prob. after an Arabic word, is to be rejected on formal as well as semantic grounds.]

"Evaluate to constants" and "evaluate to constants for all values of x" are two different things.

The implicitplot issue is not really a bug: it's the loss of an undocumented feature. The help page ?implicitplot states that the endpoints a,b,c,d must evaluate to constants (and AFAIK has always stated that). Here's a work-around. Instead of implicitplot(f, x = a(y) .. b(y), y = c .. d), try this: plottools[transform]((t,y) -> [a(y)*(1-t)+b(y)*t, y]) (implicitplot(subs(x=a(y)*(1-t)+b(y)*t, f), t = 0 .. 1, y = c .. d));

How about coding g to return NULL (instead of the identity) when the condition f is not satisfied?

DETools is, I think, just another name for DEtools. One of the few examples where Maple forgives a change of case. I agree that the help system could stand a lot of improvement. For example, a reasonable search feature should allow wild-cards, searching for phrases, and a choice of case-sensitive or insensitive. Or you could just put the Maple help system on-line and let people search it with Google...

I really don't understand what you mean. I can't make sense of your worksheet. An objective function can't be a matrix, it must be a scalar. Matrices can be involved in calculating it, but in the end it must come down to a scalar expression. Also your "constraints" don't look like constraints to me. Cheers, Robert

I really don't understand what you mean. I can't make sense of your worksheet. An objective function can't be a matrix, it must be a scalar. Matrices can be involved in calculating it, but in the end it must come down to a scalar expression. Also your "constraints" don't look like constraints to me. Cheers, Robert