Hi there!
I have a system of four non-linear equation that I can solve with fsolve after having provided the parameter values. I wrote a procedure which passes the parameters values, define all the equations and call for fsolve which provides the solution value for all the four unknowns.
Now, I would like to plot each solution against the input parameters passed to the procedure. In other words, I want to make some comparative statics which shows as the solution changes as the parameters change. Of course, I'll make only two parameters varying simultaneously.
I tried plot3d, but it doesn't work, because the procedure is not really a function I guess.

The attached file solves a system of equations in a couple of seconds in maple 9.5
But in classic worksheet maple 10.04 after many minutes it gobbles up gigabytes of memory and then ends with an error.
The file belows shows the details but it has the form
sys:={eq1,...eq22}:
solution:=solve(sys,{var1,...var22}):
Any comments very much appreciated.
Download 2129_No Solve.mws

Hi.

I am trying to debug a small piece of code I've written.

I have a procedure for solving some quite complex equations. For single points in space.

I have a procedure that:

has some quantities passed to it,

brings in a 2 by 80

Does a for loop for each of the rows in the data, to take the first col value, and puts that along with the vars passed to it into the first procedure. It then works out the difference between the value given by the first procedure and the second col. Squares this and adds it to the total.

I'd like to use the NPLSolve minimize function to minimise this total squared sum of differences, by passing differnt values to the second function.

September 04 2006
yvette 8
Hi
I'm new to Maple. I've had it for years and am just now getting into it. My problem is how to simultaneously solve a set of equations that feature some nonlinear terms. This isn't a set ODE's. They are algebraic equations with nonlinear integral terms like, I2:=int(cos(Pi/2/Theta*e)^4.545*sin(e)*cos(e-phi),e=theta..Theta); There are 3 variables to solve for after the variable theta has been specified. Equation 1 has the nonlinear terms and the other 2 equations are linear. I can post all 3 equations if someone can help.
I saw an example on this site for a vibration problem solved with the Runge-Kutta method but the dsolve command was used and mine aren't ODE's. I have version 7.

August 31 2006
Mak07 8
I am solving a set of equations with 4 variables. The solve comes out as an unordered set each time and I cannot figure out how to sort them. Btw, I am using Maple V Release 4 (yes it is old. :-))

So here is the results of the solve

sols := {b1 = 84.92147612, b4 = 87.31363038, b2 = 101.6273403, b3 = 86.10094107}

What i need to get is either the solution ordered {b1,b2,b3,b4} or the indices of the variables in order. I have tried the following:

Isort:=proc(L) local a,i;

> a:=sort([$1..nops(L)],evalb((i,j)->L[i]<=L[j])); [seq(L[i],i=a)],a end:

as recommended from another post and i get the following error:

Hi,
I'm very new to Maple. I have a set of equations. 16 equations with 16 unknowns, so it is possible to solve for 16 unknowns. I can solve using matrix if all of these equations are linear using my calculator; however, 2 out of the 16 equations are non-linear (x^2...ect) equations. I would like to use a software to solve for it.
Is there a way to solve these 16 equations using Maple?
If there is, please show me how, the more details the better for me because I'm very new to Maple and not very familiar with using Maple user interface.
Thanks

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;**