## Lable a plot...

Hi, obviously a very simple question, but not for me: I plot 3 graphes into one plot by : plot1 := plot(pts, x = 0 .. 5, y = 0 .. 1000, style = line, color = red); plot2 := plot(pts2, x = 0 .. 5, y = 0 .. 1000, style = line, color = blue); plot3 := plot(pts3, x = 0 .. 5, y = 0 .. 1000, style = line, color = green); G := textplot({[1, 1, "function"], [.5, .75, "derivative"]}); display(plot1, plot2, plot3) I tried to use texplot to lable the achses but it did not work. Is there another way to do it?

## fortuna's wheel

by: Maple

I was considering what sorts of "normally coded" things might get broken by the loading of a Maple Library package and the ensuing rebinding of names.

And so I tried this,

```> with(RealDomain): # rebinds sin

> convert( cos(x), sin );
sin(2 x)
1/2 --------
sin(x)
```

I was actually surprised to see that work OK. I was expecting `convert`...

## speed of mysql database connection...

I loaded a 1600*3 matrix into Maple 12  from my mysql datbase on my computer and it took 3 minutes to load it .

I assume that the speed will be increase significantly if I had a fast internet connection ( both up and down ).

My Internet connection (tcp / ip) is extremly slow !!    Is this correct ?   Are there any other way to speed up the data exchange ?

## Plot a list...

Hi experts, I am producing a List X[n]. After that I just want to plot the values X[n] := [n, P[n]] with n on the x axw and P[n] on the y axe. for i from .1 by .1 to 5 do n := n+1; P[n] := (i*2+3*i^2) X[n] := [n, P[n]] end do; X[1] Unfortunately I get the error message and an empty 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

## solve numerically a pde system...

Hi,

I am a relatively new user of Maple, and I try to solve numerically the following PDE system :

> pde01 := diff(c(z, t), t) = (diff(c(z, t), z, z))-(diff(c(z, t), z))+k*(a-c(z, t));

> pde02 := diff(b(z, t), t) = (diff(b(z, t), z, z))-(diff(b(z, t), z))+k*(a-b(z, t));

> cl1 := c(0, t) = piecewise(t <= 0.3, 100, 0.3 < t and t <=0 .5, 200, 0.5 < t, 100);

> cl2 := c(l, t) = b(l, t);

> cl3 := (D[1](c))(l, t) = (D[1](b))(l, t);

> cl4 := b(L, t) = a;

## How can I prove if the set is empty...

I have a little problem. I have some linear unequalities and I wan't to prove if the following set is empty.
S:={(a,c) | (a-2*b-d+2*c)*delta <= d-c-a+b, a-b >= d-c, a>=0, b>=0}

b:=2;
d:=5;
delta:=2;

I have proved it like this:
solve({(a-2*b-d+2*c)*delta <= d-c-a+b, a-b >= d-c, a>=0, b>=0}, [a,c]);

## approximation with maple...

i have

p(n):= (2310*n^5+5775*n^4+5019*n^3+(3507/2)*n^2+(409/2)*n+5/2)/(27720*n^7+97020*n^6+132300*n^5+88200*n^4+29400*n^3+4410*n^2+210*n)

how can apprximate p(n) with another polynomial (say: a second degree polynomial in n) or a rational function (ration of two second order polynomials) of less degree of n? and how good is that approximation

## Grouping negative and positive terms...

My output consists of a lot of terms (100+) and I need to isolate all the negative (positive) terms. Can anyone help? Thank you in advance.

## set ordering change

by: Maple

The following type of difference in behaviour, due to deterministic ordering of sets as introduced in Maple 12, may affect implementations of some algorithms.

```    |\^/|     Maple 11 (X86 64 LINUX)
._|\|   |/|_. Copyright (c) Maplesoft, a division of Waterloo Maple Inc. 2007
<____ ____>  Waterloo Maple Inc.
|       Type ? for help.

> seq(x, x in {a,b,c,d,e,f,g}) assuming d>0;
...```

## how to manupulate algebraic expression...

I have:

a(n):=(27720*n^(6)+83160*n^(5)+93030*n^(4)+47460*n^(3)+10689*n^(2)+819*n+5)/(27720*n^(7)+97020*n^(6)+132300*n^(5)+88200*n^(4)+29400*n^(3)+4410*n^(2)+210*n):

now i want to multiply by (n+1/2) that is

a(n)*(n+1/2)

now i want to express it in a simples form. may be like this:

c(n) + d(n)/p(n)

## How do I use the if statement in combination with ...

Hello, this is probably painfully simple but I cannot figure it out... so there it goes

there are four set of equations, but only one solution can be assigned to the parameter p (which is the outcome of R1, R2, R3, or R4).

1: if `and`(x4 = 0, x1 > 0) then assign(solpR1) end if;

2: if x2 = 0 then assign(solpR2) end if;

3: if `and`(x1 = 0, x4 = 0) then assign(solpR3) end if;

4: if `and`(x3 = 0, x1 = 0) then assign(solpR4) end if;

## Positive random numbers generator...

Hi experts, I generate two random variables R1 and R2 R1 := random[normald[mu[1], sigma[1]]](1000); R2 := random[normald[mu[2], sigma[2]]](1000); Now I want just the positive numbers of it and save them under K1:=R1^+ K2:=R2^+ Thanks for your help! Regards, Marc

## Need help to find maximum!!...

Hello, I am new with Maple and I am searching a function for the following problem:

I have a vector,
V:=[1,4,8,2]
the maximum of this vector is 8, but I want to know  where the maximum ist. Here it the third entry of the vector.
Is there a function in Maple which gives me the 'place' of the maximum (here 3)??

Thanks for your help.

Helena

## Solutions of a function....

I am new to the joys of Maple and have become a bit stuck.  How do I find the solutions of the following function:

23*sin x + x - 1 = 0

Do I need to plot a graph first and go there?

Many thanks,

Dante.