## Execution and UI components...

Hi, I have a matrix containing data read from an external file. I would like the user to select a colon number using a List box and, based on this number, build the resulting vector from the matrix. Is it possible to ask Maple to evaluate some parts (execution groups?) of a worksheet with some command (not menus)? Thanks.

## Difference Between "&xor" and "∨"...

Does the notation (&xor) stand for the logically exclusive operator "or" where both propositions of this operator cannot both have the truth value "true" ? Also, does the notation "∨" represent the more widely used logically inclusive operator "or" where it's possible for both operands to be true ? dc.

## Maple Connect...

Does anyone here use or has ever used Maple-Connect ? Also how long were you using Maple before first attempting this ?

## Creation of a simple datafile...

How do I generate a datafile (ascii-type) for the following general case: y1:=f1(x); y2:=f2(x); ... ym:=fm(x); so that the first column will contain selected values of x from x0 to xN, the second column will contain the corresponding f1(x0..xN), the third f2(x0..xN) etc.? Thanks, Miran

## Strange results of a numerical integration...

I try to calculate a numberical integration in 2 layer for loops(outer 21 times, inner 128 times): evalf(int(erfc(sqrt(B*xgms1*x/(x*xgmi1+xgmn1)))/gamav*exp(-1*x/gamav),x=0..infinity)), i.e., the kenerl is erfc(ax/(cx+d))×exp(-ax). But when "gamav" > 100000, the calculation time is too long to bear. So I try to do some approximation and change the upper bound into 10*gamav, 30*gamav, 50*gamav and 100*gamav. But I got the following results: BER1a1=0.0001004773804, BER1a2=0.0000365034983, BER1a3=0.0000000096250, BER1a4=0.0000000000001. The trend of results is bigger the upper bound smaller the results. Obviously, the results is wrong. When "gamav" is a smaller number, such as 1000, the four integration results is the same as when the upper bound is "infinity".

## Evaluating polynomials without knowing variables?...

Hello! I would like to do something that I really think should be simple. Suppose I have a polynomial P := x^2 + y If I want to evaluate it at the point [1,2], I could say: eval(x=1,y=2,P); But suppose that I didn't know the form the variables in the polynomial would take. Or suppose that I knew they were of the form x1,x2,x3,...,xn. Given a vector of size n, how can I evaluate my polynomial at that point? Thanks! Susan

Here is my problem: I am trying to plot this: y=(pi(sqrt(4-(x^2)))/((x^2)+4) but i get this error, when trying to plot. Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct Error, empty plot please help ASAP

## vector length in Maple 10.0 Classic worksheet...

Hi. Anyone knows a command on how to calculate the norm (length) of a vector? For example: Maple input: START >restart:with(linalg):#I know this package is obsolete, but my Teach only teaches theese commands.. >u:=vector([1,1,1,1]);#a vector i defined >LengthU:=sqrt(u^2+u^2+u^2+u^2);#This is how I calculate the length theese days... END Anybody knows a command, so that my third line will not be neccesary? TIA

## Syntax for Commands in the Logic Package...

After reviewing the help pages on the Logic package I noticed that the commands used in examples usually contained an ampersand "&" before them. Does this in any way alter the meaning of the logical operator or (connective) in any from it's usual meaning in standard text ? for example, is &iff "if and only if" ? does ∧ stand for "and" ? does ∨ mean the logically inclusive "or" does &implies mean "if antecedent then consequent" ? and so forth... Dan

## MATLAB coding...

Hello members, My question is out of maple primes, but i was wondering if one of the members is and expert in MATLAB coding. I am trying to write a MATLAB code for numerical integration for a double exponential equation of the form i = io(exp(-alpha*t)-exp(-beta*t). The problem i am facing is how to eliminitate the error as the integration is taken as the area under the curve, say from time t=0.0 to t=25e-6. Your comments in how to solve this problem is highly appreciated. Regards, JacquieD.

## Shading under a curve in a 2D plot...

I am wondering how to shade a portion of the plane under a curve from say x=a to x=b. To be more specific suppose I have the function f(x) = 5 - x^2. I want to plot this function and shade the region under this curve and above the x-axis from x = 1 to x=2. How can I shade it with a solid color; and how can I shade it with a striped region. I imagine there must be some "shade" command or option. Your assistance will be appreciated. Tom

## Tautologies...

Can Maple be used to see if propositional logic sentences with arbitary propositional constants are tautologies ? i.e. (if they are always true under every possible interpretation or arrangement of the truth values true and false).