I have been using solve in Maple 9.5 to solve a system of equations with a very large solution (90,000 terms provided in about 10 mins). Access to Maple 9.5 was unvailable so I used Maple 9; I gave up waiting after several hours and seeing memory use go up to 1Gb. Is there a big difference in the coding to explain this. Also, I don't yet have Maple 10; does it have any further improvements?

As currently programmed, fsolve() does not do numerical derivatives for systems of equations. The reason for this is that subs() is used instead of eval() when evaluating derivatives. [Note: jacob is the symbolically defined jacobian of the system of equations and lsub is the sequence of appropriate numerical substitutions (not the "list" of substitutions the mnemonic might suggest).] The original statement (in `fsolve/sysnewton`) is:
A:=traperror(evalf(subs(lsub,jacob),Digits-5+n));
The functions evalf() and subs() apparently do no know how to work together to produce numerical derivatives. However, the following statement does work.

I have seen a number of forum questions concerning showing students the steps in a problem. There seems to be some confusion about how to do this reliabley and easily.
A method I have found useful is seen below:

I wish to extract the coefficients associated with a particular variable.
I have assigned the results of a symbolic solve of a system of equations (sol) using
assign(sol):
One of the assigned variables in (sol) is ROLL and the symbolic solution is of the form
ROLL;
200*a*b^2*VAR1 + 3000*b*VAR2 + 1500*cos(c)*d*VAR1 . . .
(the actual expression is hundreds of line long and each VAR is randomly distributed in the expression)
How do I isolate the coefficients associated with a specific VAR
eg for VAR1 I want to be able to make the assignment
coefVAR1:=(200*a*b^2)+(1500*cos(c)*d)

August 14 2006
Rick 28
Hi all,
I'm currently using the diffalg package to eliminate unknown signals and use the known ones for diagnosis (fault detection). At the moment, I have generated a lot of smaller equation systems from the large one I'm trying to diagnose. However, I get a lot of equation systems (too many to solve all of them), some goes very quickly to solve, others take a loooong time (too long for my poor computer).
My question is, is there a way to "rank" the equation systems so I can start with the ones that have the highest probability to solve (other than the obvious number of equations in them)

This is my first time using Maple - so I don't even know where to start...
Hopefully I can make this clear...
example problem:
f(x) = 2.3x
g(x) = ax^3+bx^2+cx+d
h(x) = px^2+qx+r
l(x) = kx^3+mx^2+nx+s
I was able to find the correct syntax for Maple to calculate the first and second derivatives of the functions above. Now I have to write out a system of equations using the original functions and their derivatives...once I have the system of equations then I need Maple to solve for each variable...what is the proper syntax for all of that? Also, for Maple to calculate the derivative I used "diff(f(x),x)" and "diff(f(x),x$2)", so how do I get those derivatives into my system of equations?

I have a Matrix (M) and want to extract the actual equations from the following M.x=x; where x is a vector of variables that I want to solve for.
I would like to be able to extract the actual equations (the values for M are determined elsewhere), for example, 3 x1 + 4 x2 + 2 x3 = x1.
How can this be done in Maple?
Thanks.
Brian

>e1r := -1.5;
> e1i := 12.455;
> e2r := -.022269812;
> e2i := .25368881;
> E1 := e1r -I*e1i;
E1 := -1.5 - 12.455 I
> E2 := e2r -I*e2i;
E2 := -0.022269812 - 0.25368881 I
> nz1 := RootOf(E1*NZ^4 - NZ^2*(2*E1^2) + E1^3 - E1*E2^2=0,NZ,index=1);
Error, (in content/polynom) general case of floats not handled
ok so what is wrong with this? its all simple equations and complex floats, the syntax for rootof looks correct...

fsolve fails when eqs are 2D integrations

**> restart;**

**> infolevel[all]:=0;**

**> infolevel[evalf]:=0;**

hi;
i have a system of 4 equations depending on each other, which cannot be solved explicitly. using the fsolve command reports a solution, however there must be whole bunch of possible quadruples.
i tried to fit the fsolve command in a loop, ignoring the previous solutions, without any success.
can anybody give me a hint on how to come up with the whole range of possible solution?

First time posting here, hoping to find some help, and I may try to help others.
I have a set of 8 equations. Each of the 8 equations are in terms of two variables. For example:
x1 = f1(theta1, theta2)
x2 = f2(theta1, theta2)
x3 = f3(theta1, theta2)
x4 = f4(theta1, theta2)
y1 = f5(theta1, theta2)
y2 = f6(theta1, theta2)
y3 = f7(theta1, theta2)
y4 = f8(theta1, theta2)
the functions f_j are not neccesarily linear and are fairly complicated with many factors. I need to remove (eliminate) the theta1 and theta2 terms from the set and be left with a new set of equations that is in terms of x_i and y_i.

I am trying to compute some Lie brackets in Maple but am having trouble with the output. The first five few terms that I computed are small enough that they will display with pretty print. However, the sixth term gave me the error 'Large output of more than 1000000 nodes' and it couldn't display. I turned pretty print off and eventually got it to display the sixth term but now I can't get the seventh or eighth terms to display even with pretty print off. Every time I try to output the expression for the seventh or eighth Lie bracket Maple just stalls out. Since it can compute the terms that I need but not display them is there a way I can export the hidden content to a text file or some other format so I can copy and paste the equations into Matlab?

I had three questions, but two were about series solutions to linear ode's, and I just discovered the wonderful Slode package...I learn something new about Maple every single day! I still have one question though...
In the help page for the laplace command in the inttrans package, it is indicated that, when transforming ordinary differential equations, initial values can be set and incorporated into the transform, but I haven't figured out exactly how to do this, and I didn't find anything else on the help page.
Thanks a lot for any suggestions!

I've been trying figure out how to code up arbitrary volume and surface integrals in Maple. I know that Maple has the VectorCalculus package but there doesn't appear to be a way to specify a volume integral (where the infinitesimal is dV). Also, there doesn't seem to be a way to specify a surface integral without defining the surface in advance (i.e., integrate over S with an infinitesimal of dS). In both cases, I'd like to have general integrals where I can specify the bounds at a later time (e.g., inert integrals).
I know that there is the triple integrals in the student package but they aren't the same as a volume integral.

Is there a way to create periodic piecewise functions in Maple 10 for use in solving differential equations with periodic forcing functions?