## LSSolve...

how do i use LSSolve to find least squares solution to a function and plot it. Thanks

## Maple license-error: "System clock has been set ba...

Since I accidently changed my system clock to a time in the future and set it back correctly, I get an error when Maple starts. It's an license-error more specific: FlexIm error: -88,309 "System clock has been set back" Maple asks to reactivate, once done that successfully Maple says that after starting Maple again everything will work properly. But it doesn't work, I get once again the same error and the question to reactivate. The error is known by MapleSoft, I got this information: "FLEXlm checks the computer for files with a timestamp beyond the current date. If there are files with a creation date in the future of what the current system clock reads, FLEXlm will return this error. These files must have been created when the clock was set incorrectly. We suggest the user conducts an advanced file search to find the files that are causing the problem."

## assume statement in Maple...

Hi, I have a function that looks like: f := (x, y, z) -> -(y^x) + z; Now, if x = infinity, y > 1 and z < infinity, the value of the function f should be -infinity. How do I get that result using Maple? I was trying to use commands like simplify, assume and assuming, but I could not make it work. Any help would be appreciated... Thanks!

Hello, all! I have a linear system of real numbers. I copied the example in the tutorial for using LinearSolve and converted my matrix to a float: with(LinearAlgebra); my_solve := proc(A::Matrix) local sz, local_A, B, sol; sz := Dimension(A); local_A := Matrix(A, datatype=float); B := Vector(1...sz[1], 1); sol := LinearSolve(local_A, B); end proc; And when it solved, it got the wrong answer!! It would produce a solution that simply didn't work. When I removed the float conversion step, and just used my original matrix, it worked perfectly. I would love to understand this better... is it because of rounding?

## Working with an array...

I am having issues creating an array and dividing by the values in the array. Any tips on how to make this a quick and painless process?

## Curve Fitting Graph...

I know how to use the Curve Fitting Assistant to generate the least squares regression line for my data points. However, I need the graph of those data points and the regression line shown in the Assistant itself (with the circles / red line). How do I past / recreate that graph in the document itself?

## Help Understanding the Working of a Procedure...

Here's an example procedure that I need help with in order to figure out how it produces certain cases of it's output. First, in the case when the argument n is negative does the procedure call itself again in the denominator of the fraction and return the value of the last line of the procedure (inside the inner call to itself)? I also assumed that the special identifier procname was not in unevaluation quotes in order to allow evaluation. Next, I also don't understand how the output for cases when the exponent n is even is produced. What's really confusing is the use of the anonymous mapping (x -> x.x), and also the meaning of the entire expression after the word then. Is that a multiplication of the two expressions in parentheses ? i.e. (x -> x.x)(procname(X, n/2) > Pow := proc(X, n::integer) if n <> x.x)(procname(X, n/2)) else X.procname(X, n-1) end if end:

## what's wrong? int(f,x)...

Hi! i want to know the length of sin(x) from a to b. This function sqrt(1+cos(x)^2) >= 1 int(f,x) must be > 1 So...try to do it,plot, and see what happen. is correct?

## Toda Lattice Second Order Coupled Differential Equ...

Hello, I am trying to analyze the numeric solution to the following equations - now what I want to do is a little different, I want to plot u_(n)(some number) as a function of n. This would show me the progression through the particles/distance rather than with respect to time. Here is the code: > with(DEtools): > n:=5: #(n can be as large as 500..) > > sys:=[seq(diff(u||i(t),t\$2)=exp(u||(i+1)(t)-u||i(t))-exp(u||(i)(t)-u||(i-1)(t)),i=2..n-1)]: > eqn1:=diff(u||1(t),t\$2)=exp(u||(2)(t)-u||1(t))-exp(u||(1)(t)-u||(n)(t)): > eqnn:=diff(u||n(t),t\$2)=exp(u||(1)(t)-u||n(t))-exp(u||(n)(t)-u||(n-1)(t)):

## Duplicates on lists....

Hi Hope anyone can help. When using this syntax in Maple 10: >restart:_EnvAllSolutions:=true: f:=(x,y)->x^3*y-2*x^2*y+x*y^3; GRAD:=[diff(f(x,y),x),diff(f(x,y),y)]; STATS:=solve(GRAD,[x,y]); I get the following output: 3 2 3 f := (x, y) -> x y - 2 x y + x y 2 3 3 2 2 GRAD := [3 x y - 4 x y + y , x - 2 x + 3 x y ] STATS := [[x = 2, y = 0], [x = 0, y = 0], [x = 0, y = 0], 2 [x = 5/4, y = 1/4 RootOf(_Z - 5, label = _L2)]]

## How do I make 3D surface plot from Matrix?...

Hi, How to make surface plot from elements stored in matrix of form [x,y,z]? Let's suppose I have the following matrix: >A:=matrix([[1.00, 1.00, 167.76], [1.00, 2.00, 95.588], [2.00, 1.00, 500.64], [2.00, 2.00, 335.51]]); The first argument from the lists is value for X axis, the second argument is value for Y axis and the third argument is value for Z axis. For example: x=1, y=1, z=167.76 x=1, y=2, z=95.588 x=2, y=1, z=500.64 x=2, y=2, z=335.51 How to make such plot in 3D?

## Maple's 3 Valued Logical System...

Is Maple 10's logical system called a three valued one simply because of the value FAIL, in addition to the truth values true and false ?