## using assuming...

Hi I have the following command: > LinearSolve(E0,Z,free=R) assuming real; when I execute this I get: Error, (in assuming) when calling 'LinearAlgebra:-LinearSolve'. Received: 'unexpected argument(s): free = R, LinearAlgebra:-LinearSolve' I am not sure why? can anyone explain? Without free=R it works fine...

## Maple 7 and Windows Vista...

I have used Maple 7 under Windows 2000. Now I want to port it to Windows Vista. It seems to work well, but only when instructions are introduced onto the Maple screen by drag and drop from an external text file. When I try to type numbers or literals nothing appears on the screen. This peculiar behaviour is not observed with other programs, Mathematica (4.2), for example. Additionally, when I try to save a file, the Maple screen disappears immediately. There must be a simple solution of these problems, but I have not yet found it. Any help will be welcome. Thanks! Willy

## Why does Maple uses N as the denominator and not N...

It appears that Maple uses N as the denominator and not N-1 in calculating a covariance matrix in the Statistics package. Why? Harry Garst

## How to stop maple...

Hi I have a 8x8 jacobian matrix from a nonliniear system of pde's I was attempting to get maple to find the eigenvectors however it runs and runs and never stops. I have let it run for hours and to me it looks like in its current form its just too messy for maple to solve. The question is how do I get maple to stop evaluating?? The "interrupt current operation" button is grayed out, even though the lower left corner of the screen has a flashing dot with the words "Evaluating..." next to it. I am attempting to simplify the jacobian so that maple can succeed but each time I make a change I have to kill maple and restart to try.

## fit...

To read data from file and fit it to a known equation,for example y a*x+b I used the commands: fs := ImportMatrix("C:\\Fit\\test.dat"): with(Statistics):eq:=Fit(BesselK(a*x+b,fs[1....200,1],fs[1...200,2],x); but I do not know how to let Maple calclate the values of y for each x after I knew the parameters a and b from the fitting.and how I can plot the fitting equation to compare it with the plot of the data to know is the fitting is good or know.

## Help! I just couldn't get Maple to calculate this ...

I want to find the real part of the following expression, but I keep having difficulty: simplify(evalc((zks/(alphas+I*vs)*(exp(-I*times*vs)-exp(-I*times1*vs-alphas*tds))))) assuming real; Maple refused to do it... what can I do? Thanks!

## Error, (in march) cannot lock repository...

I admit that I am clueless to this error message produced by 'march' > march('delete',libname[1],'a'); Error, (in march) cannot lock repository and a similar message produced by Delete from LibraryTools: > Delete('a',libname[1]); Error, (in march) cannot lock repository because: 1. There is my personal Maple library file in the path specified by libname[1]. 2. Issuing command > ShowContents(libname[1]); returns the library content showing that "a.m" file/name is there. 3. The library attribute is not READONLY but it is WRITABLE. What is going on? Any suggestions?

## Display of variable in Equation editor-does not pu...

I am trying to display multiple integrals with the equation editor in my questions. If I use the name \$eqn, for example, it does not put that in HTML format. It may leave it: x^2 +y^3. I have tried putting my variable into HTML in the algorithm but then it will not display at all. Any suggestions? I have avoided the editor as much as possible but it is impossible with definate integrals.

## Graphing an inequality...

Maple folks, I am a Maple newbie. I am trying to figure out how to graph an inequality: x + y

## Using Maple to do difficult integrals......

Hi all, I am just playing around with Maple, with curiosity, to see how smart it is and how much can I rely on it for work... Here is a probably difficult integral, I couldn't get Maple to do it: assume(b>0, T>0, a>0, w>0); int(exp(-b*sqrt(w))/sqrt(a^2+w^2), w = T .. infinity); Is there a way to get it work? I tried a few numerical values, this integral should converge... right?

## Numeric evolution of a system of ODEs...

Hello, I have a problem with a system of ODEs. The three differential equations are as follows: diff(c(t),t) = 2*(c(t))^2 + 21/50*c(t) - 1/100*(h(t))^2 - 1/5*c(t)*h(t) - (9/2000)*h(t) + 49/4000; diff(h(t),t) = h(t)*(c(t) - 1/5*(h(t)-1)); diff(k(t),t) = 8/100*k(t) - h(t) - 1/5*k(t)*h(t); `diff(c(t),t) = 2*(c(t))^2 + 21/50*c(t) - 1/100*(h(t))^2 - 1/5*c(t)*h(t) - (9/2000)*h(t) + 49/4000;` `diff(h(t),t) = h(t)*(c(t) - 1/5*(h(t)-1));` `diff(k(t),t) = 8/100*k(t) - h(t) - 1/5*k(t)*h(t);` As t goes to infinity the three variables c(t), h(t), k(t), respectively, approach certain values -in this setting `1/50`, `11/10`, `55/3`, respectively- with the values of the derivatives converging to 0. (The point is saddle path-stable.)

## How to decide the location and type of singulariti...

Hi all, I am just curious about this problem, which has been in my mind for long time. I have seen some complex-valued functions, which are not in closed-form. For example, the complex-valued functions are defined by ODE: y'(t)=a+b*y(t)+c*(y(t))^2 + ... where the numbers in above ODE are complex-valued and the complex-valued functions are defined by functions of y(t), such as exp(y(t)), etc. Such ODEs can only be solved numerically. Sometimes even a closed-form solution is available, we would rather choose to solve it numerically because the closed-form solution often involves hyper functions and super complicated expressions.

## returned expresion from solve(eqn,c) doesn't sol...

I have the following:
```>                 /             /         2          \\
>              1  | 2    2      |/ 2    2\       2  2||
>       eqn := - +\b  + a , sqrt\\b  + a /  - 4 a  c // - c
>              2
(1/2)
1  2   1  2   1 / 4      2  2    4      2  2\
eqn := - b  + - a  + - \b  + 2 b  a  + a  - 4 a  c /      - c
2      2      2
>                          solve(eqn, c)
2    2
```