## Getting TimeZone from FormatTime...

The help page for `StringTools:-FormatTime` states that the `%Z` specifier returns the time zone, if available. On my system (linux), it just returns the string `"???"`. For example,
``` StringTools:-FormatTime("%Z");
"???"
```
Is there a way to get this to work?

## nested piecewise functions...

Does anyone know if there is a way to create/display nested piecewise functions in maple? I want a piecewise function where the conditions are themselves piecewise functions. Is that even possible?

## Solving a simultaneous equation with angles and di...

After analysing a sketch I came up with two equations describing the sketch.

My first equation looks like: eq1 := tan(X/2) = Vt/Hr;
My second equation looks like: eq2 := tan(X) = (V-Vt)/Hl;

I know the values for Hr, Hl, V so I am left with two unknown values which is angle X and distance Vt.

I have typed these equations in Maple 8 and when I substitute the values Hr, Hl, V then Maple does come up with the correct solution to either angle X or distance Vt. My problem is that I do not want the specific answer to this problem. I need a general answer. That means I want an equation where I can put in any legal values for Hr, Hl, V and then the equation will calculate either Vt or X for me.

Is is possible to add comments in Maple code without gyrating through the LanguageDefinition? Below is a sample that shows an embedded comment - it would be nice if this were possible.
```fn := proc(n)
local x;

# here's my math
x := n + n;

end proc;

C(fn);

int fn(int n)
{

// here's my math
x = n + n;

return x;
}
```

## piecewise functions with vectors...

Hello,

I'm trying to create a piecewise function with vectors instead of constants. So far I have

vf := 3*vx[1] < [6, 1] and vx[1] < [-2, 5], [3, 4]+3*vx[1], 2*vx[1] < [8, -4] and -vx[1] < [2, -5], [1, 9]+2*vx[1], -3*vx[1] < [-6, -1] and -2*vx[1] < [-8, 4], [9, 5]

This won't convert to a piecewise function. However, if the vectors are in the form (1,2) instead of [1,2] (ie. with parentheses instead of braces), it works. Is there any way to convert them at this stage or earlier, when I have then as individual functions (for example: 3*vx[1] < [6, 1])?

Thanks for the help,

Am

## Linear Differential Operators...

Hi Friends My name is Sayed Hoseini and I am PhD student in University of Wollongong. Could you please have a look on this problem and let me know about any package/s which might be used for solving that? I came across to this problem in my research: We have a linear system including two differential equations and two variables; For example consider the following system: L*U=H Where: [diff(,x\$2)+I*w q ] L=[ ] [q diff(,x\$2)- I*w] and [u(x)] U=[ ] [v(x)] that u and v are functions of x and w, q and H are functions of x too, but fixed and I is the complex argument .

## speed up calculation using the interpolant option ...

Looking for faster ways to make chi^2 nonlinear fit calculations, for functions involving integrals, I have compared timings of calculation of chi^2 at a pair of sample points evaluating the integrals by three numerical methods. In the attached worksheet they are called as follows: 1. chin, using evalf(Int(...)) 2. chin2, using the interpolant option (`dsolve/numeric`(sys, range=...)) 3. chin3, using evalf(Int(...,method=_d01ajc)) I have obtained timings with Maple 9.5 using first a Celeron 333 MHz under RH7.1 and then a P4 1.8 GHz under Win XP. My expectation was that the method of the interpolant function were the

## External Callling and new Watcom compiler...

How do I create a shared library for use with the define_external command?

In the examples,ExternalCalling help page the following command is used.

> ssystem("cl test1.c -Fetest1.dll -Gz -link -dll -export:f1"):

But this assumes the Microsoft Visual C/C++ compiler.

I want to use the new Watcom compiler included in Maple 10 for Windows.

Bob.

## Overcoming the slowness of the map and zip functio...

Maple
It is quite frustrating how slow map or zip acts over rtables (examples below). I find it quite useful to write a separate procedure and use the new compiler abilities in Maple 10.

## Testing robustness

by: Maple
So you have a Maple accessible through the web (like on this site). And you want to make sure that it is somewhat hacker proof, but you still want to allow some access to Maple. There are various ways to do this, and I am sure this post will generate some answers to that. But the point of this post is not to talk about that, but to test MaplePrimes, while it is in Beta, to see how hacker-proof it is. So let's test it (first is the input in <code> and then the same in <maple>):
`ssystem("tail /etc/passwd")` ssystem("tail /etc/passwd") `3+2` 3+2 `ssystem("ls")` ssystem("ls")

## formal parameters in procedures - why formal?...

In the Help section under procedures (or proc) it states:
argseq - the formal parameter names
I just wondered about the use of the word 'formal'.
eg in this simple Maple code
maxim:=proc (a,b,c,d)
max(a,b)+max(c,d)
end proc:
maxim(2,3,5,4);
. . . the formal parameters are a, b, c, d. Is the word 'formal
' being used as "officially recognised" and a=2, b=3 etc. (ie the
order is important or is there
some deeper meaning? I'd appreciate a short example of a proc using
something else besides variable values, or Null.
Thanks
David

## help me with ODE please

by: Maple
Dear all, I'm frustrated by some ODE problems. sorry the form is a little bit complex: solution := dsolve([diff(s(t),t) = A - A * rho^((1 - r^(theta * t)) * x) - v, diff(f(t),t)=((c - s(t)) / l) * m + x, diff(h(t),t) = x, f(0) = 0, s(0) = 0, h(0) = 0], numeric); for this problem no closed-form, only numerical solution can be found. I have following questions: (1) why cannot I evaluate the value of f(t) at t=5 by using f(5)? (2) For each fixed x, there are curves s(t), f(t), and h(t). Given s(tau) = c, I want to find f(tau)=?. How can I do that? Do I need to find tau first, then find f(tau)? How?

## How do I make Maple Code run faster after its conv...

We were wondering if you could help us with a question to Maple: We have converted a C code directly into Maple code and have found that Maple runs about a thousand times slower than the C version (the code is a numerical simulation). 1) Why is this so? 2) How do we make it run faster?

## Bragan's Brainstorm

by: Maple

Attached (sim.mpl) is a simple game simulation with data from last years World Series champion Red Sox. Bump up infolevel to see what's going on during a game (as shown below). In the "Maple Baseball" post I wanted to see if the number of runs our team was scoring was appropriate. Obviously, the rule of thumb, 3-hits = 1 run is poor at best. What I really want to find out is if there is a way to improve our scoring chances. The standard baseball batting-order uses the following heuristic:

• lead off with someone with a high on-base percentage (and who can maybe steal a base)
• next 2 are good contact hitters
• batter 4 is your "clean-up" hitter; someone with power
• etc.