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

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 S_{xx_0} and S_{yy_0}], m=0..1) + Int( [arclengthformula applied to S_{xx_1} and S_{yy_1}], m=1..2) + Int( [arclengthformula applied to S_{xx_2} and S_{yy_2}], m=2..2.7)

Robert Israel, it works perfectly.

What does cat do?

Thank you

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 S_{xx_i} and S_{yy_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, P_x and P_y, one for x and one for y that does the following... let's take x for example

P_x(14.6) = S_{x_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 S_{xx_floor(m)}

Another example, let's say for y:

P_y(52.7) = ?

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

2. then substitute m=52.7 in S_{yy_52}

3. return the evaluation

Thank you

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

P_x(20.4) would be equal to [  S_{x_20} evaluated at 20.4 ] and P_y(20.4) would be equal to S_{y_20} evaluated at 20.4

I have tried something like this

f_x := piecewise(floor(m) <= m <= ceil(m), S_{x_floor(m)} ), but it gives me an error.

What to do?

Thank you very much, it worked

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 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 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 α_i 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 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 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 i just made up a name. The real name of the matrix is Divisions. Anyway how would I define ΔX_i to be the ith entry in the single column "Divisions" matrix? Thank you

Sorry, little typo, i goes from i to 200