## 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.

## print dsolve[numeric] result to file?...

Hi, All, I'm a Maple primer. I want to solve an ODE numerically and then save the data to file. I use: dsol := dsolve({deq,ic}, numeric, range=0..100); or dsol := dsolve({deq,ic}, numeric, range=0..100, output=operator); then how can I print the formated data for some specified t (=1..100, for example) to a data file? Thanks. David

## missing symbol...

I need the symbol for the partial derivative (something like @) in a .mws worksheet. Well, I found this feature as an operator on the new .mw platform, but I need it as a symbol. If I write a name (say PartialD) in the worksheet I want to get the symbol similar to @ at the screen.

What can I do?

Florian

## working with tensors in maplet...

I would like to construct a maplet to evaluate different objects in general relativity, say for example , metric,covaliant derivative and so on. Please help me with the procedure or a sample maplet.

## generate code for numerical integral...

Is it possible to generate C or Fortran code for a numerically evaluated integral (ie. evalf(Int(...)) )? with(CodeGeneration): and either C(..) or Fortran(...) yield the error message: Warning, the function names {Int} are not recognized in the target language (a similar error message occurs for an int(..) expression) Alejandro

## An animation of 2 curves

Maple
```f:=sin(t)*x*(1-x);
g:=cos(t)*x*(1-x);
plots[animate](plot,[[f,g],x=0..1],t=0..2*Pi);```
This blog entry was created essentially for a possibility to post pictures in comments (where attachments are not allowed.)

## multiple animations...

A student in my PDE class asked about having two functions in animation at the same time. Here is how I suggested doing this: > f:=(t,x)->sin(t)*x*(1-x); > g:=(t,x)->cos(t)*x*(1-x); > N:=50; > for n from 0 to N do J[n]:=plot([f(2*Pi*n/N,x),g(2*Pi*n/N,x)],x=0..1): od: n:='n': > plots[display]([seq(J[n],n=0..N)],insequence=true); Is there a simpler way? Jim Herod

## Why won't assume and assuming work consistently?...

I am trying to determine when one inequality implies another inequality and I am finding that assume and assuming aren't working consistently for me. I've put the code for my test run below. It seems to work the first time through when I assume mylist[1], but when I assume mylist[2] it always returns false. If I explicitly test is(x>-4) it returns true as it should but if I ask it to determine is(mylist[5]) (which is x>-4 once mylist is overwritten) it returns false? Is there a reason for this? I'm eventually going to need to put it all into a loop that works for any list--is there a way that will guarantee that it will work consistently?

## Friday test of Maple HTML

by: Maple
OK, in posting a new blog, there is an "Attachment" section... So I could add the three GIFs. They don't show up in the preview, but they did come out when I actually posted...

 > sum((-2)^k, k=1..infinity);

 > _EnvFormal := true;

## Why Maple 10?

by: Maple
As moderator of the How Do I?? (Newbies) forum, I thought I would post some information for my viewers. As a somewhat "Newbie" to Maple myself, I thought I'd boast about how amazing I think Maple 10 is (and no... this is not just because I work for Maplesoft ;). My first experience using Maple was a year ago, when I started with Maple 9.5. As expected, like any scientific software, there was a learning curve that I had to conquer.
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