## 173 Reputation

14 years, 146 days

## Hello I don't really...

Hello

I don't really understand the syntax of this method as i only see t<2?? The example I gave had only 2 equations but the real situation contains about 80 equations

0<t<1
x(t)=some expression
y(t)=some  expression

1<t<2
x(t)=some expression
y(t)= some expression

...

79<t<80

x(t)=some expression
y(t)=some expression

and then plot for t from 0 to 80

Can i do that with your method?

## thank you very much...

thank you very much

## Thank you very much...

Thank you very much

## Hello, although it works, I...

Hello, although it works, I would like to know if it would work for my application. I want to compute some arc length over an interval, lets say from 0 to 2.7

the arc length is then:
Int( [arclengthformula applied to Sxx_0 and Syy_0], m=0..1) + Int( [arclengthformula applied to Sxx_1 and Syy_1], m=1..2) + Int( [arclengthformula applied to Sxx_2 and Syy_2], m=2..2.7)

## Robert Israel, it works...

Robert Israel, it works perfectly.

What does cat do?

Thank you

## I have about 80 equations...

I have about 80 equations for x, and 80 equations for y, not functions, which are all defined in term of m

The equations are called Sxx_i and Syy_i , i goes from 0 to 80

Here is a screenshot:

http://img339.imageshack.us/img339/5290/equations2.jpg

I want to define two new function, Px and Py, one for x and one for y that does the following... let's take x for example

Px(14.6) = Sx_14 evaluated at m=14.6

In other words, the new function takes a real number m between 0 and 81, substitute it as 'm' in the equation Sxx_floor(m)

Another example, let's say for y:

Py(52.7) = ?

1. first compute floor(52.7), which is equal to 52.

2. then substitute m=52.7 in Syy_52

3. return the evaluation

Thank you

## Ok, I figured it would be...

Ok, I figured it would be easier to take car of x and y separately, so defining a function Px that gives me the x component and Py that gives me the y component. For example,

Px(20.4) would be equal to [  Sx_20 evaluated at 20.4 ] and Py(20.4) would be equal to Sy_20 evaluated at 20.4

I have tried something like this

fx := piecewise(floor(m) <= m <= ceil(m), Sx_floor(m) ), but it gives me an error.

What to do?

## Thank you very much, it...

Thank you very much, it worked

## Ok, so how would i do what I...

I am trying to assign a sequence of equations.. for example:

a_{i}+b_{i}=c_{i} where i goes from 1 to 20

how to do that

## Hello I don't know what...

Hello I don't know what happened with the post

I am trying to assign equations

But i get the invalid arguments error. What is the problem?

Thank you

## Thank you very much Robert...

Thank you very much Robert Israel and gkokovidis, it worked. So the sequence command is used to generate a list, that's useful to know I didn't know that before. I have another question:

I have defined a 90 rows 4 columns matrix named B.

I have also defined 90 variables αi where i goes from 1 to 90 and represent the number of rows in the B and C matrix.

Now, I want to define a new C matrix whose elements are computed using matrix B and the variables.

For exemple,

the row 1 column 1 element of the C matrix = B[row 1, column1]*α1 + some constant

the row 1 column 2 element of the C matrix = B[row 1, column2]*α1 - another constant

the row 1 column 3 element of the C matrix = B[row 1, column3]*α1

the row 1 column 4 element of the C matrix = B[row1, column 4]*α1

I have made up the equations but the important point is that the used variable is the same for a row, only the equation change.

the row 2 would then use α2 as the variable and so on until row 90

How would i do that? Thank you

## Hello,   I have tried your...

Hello,

I have tried your method. It almost works. I have included a screenshot so you get a better idea of the problem. It looks like it's not really defining the variables. Here's the link to the screenshot:

img15.imageshack.us/img15/729/problemxg.jpg

Thank you

## Hello, thank you for your...

Hello, thank you for your answer. Sorry I was not being clear. I have real world data I want to assign to a matrix. For example:

Divsions is a matrix (or a vector.. whichever works best)

|  29328  |
|  4328    |
| 4489     |
|  2138    |
| 48934   |

I want maple to know that ΔX1 is 29328, ΔX2 is 4328, and so on.

Any way to do that?

Thank you

## Hello, its not really Matrix...

Hello, its not really Matrix i just made up a name. The real name of the matrix is Divisions. Anyway how would I define ΔXi to be the ith entry in the single column "Divisions" matrix? Thank you

## Sorry, little typo, i goes...

Sorry, little typo, i goes from i to 200

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