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

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.

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.

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!

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?

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.

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

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?

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.)

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.

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

I want to solve the following task efficiently. I need to read data from S files (in my case S = 50000). Each file has T rows of 5 floats each. Here T=1000 is a time index and 5 is the dimension of a dynamical system. From each file I want to read the j coordinate and to assign its T values to a column in a matrix X. At the end of this process I'll have an X array or matrix of dimension T x S. How can I do this efficiently? When I use 'readdata' in order to read the Tx5 matrix from a single file into a list D, this is a fast process. But assigning, naively, the j column from this matrix to my matrix X, using a for loop,

Hi, I am Er. Vishal Jain new to maple prime. I need help in developing dynamic 2D-graphs(pi-chart, conic section etc.) in .mw and respectively shade the graph.

While posting an initial question is not problematic, when editing or adding a comment thereafter, one is presented with a box in which to compose that is partially concealed by content at the right of the screen, e.g., Active forum topics and Recent comments. One can continue to type behind the veil and have it display fine in the preview, but this seems anomalous. I have noted it on two different computers. Do others have this problem? Is there a way to work around this besides truncating ones sentences with early returns?

As per instructions at the bottom of page 217 of the user manual, I wish to alter the y-axis range of a 2D plot. The instructions say to right click the plot region. Select axes and then range, however, doing so allows one to select axes, but the menu item range is nowhere to be found in the menu as described by the manual. The menu only offers the choices of normal, boxed, framed, none, properties, labels, toggle gridlines, and set gridline properties.