| Author | Comment |
therock003
Probe
Posted: 29 May 2008
02:06 GMT
Total Posts: 9 | Hi guys,i'm a land surveyor student and you know,we use lots of coordinates and trigonometry and geometry.So anyway i want to keep matrices of coordinates,and i want to use functions that draw infromation for each element stored on a matrix.So for example lets say i have matrix 1
Point# X-Coord Y-Coord
1 50.6533 60.4570
2 65,3214 67,3213
So i want to have a function atan(Yj-Yi/Xj-Xi).
So every time i call this function i specify which is j and which is i and it draws infromation from my matrix.How can this be done? |
Vectris
Ultralisk
Posted: 29 May 2008
07:19 GMT
Total Posts: 375 | Well you will probably have to write a program for it, it wouldn't be to hard so don't worry. But by specifying which is J and which is I, the Js and the is would still match with the X and the Y coordinate from each point? Like you are not going to switch Xs and Ys from the same point.
So in other words, you cannot have Yj=60.4570 and Xj=65,3214.
Also we need to know if all your matrices are going to be 3x2. Is it possible that you will have them longer, such as not just 2 points, but 5? This would increase the possibilities for variables J and I and it is important to know that there could be more than two values for them.
Also, if J and I are representing which point the coordinates come from, why not just use the actual point they come from? So Y2-Y1/X2-X1. |
haveacalc
Guardian
Posted: 29 May 2008
08:36 GMT
Total Posts: 1111 | Calcproductions, I'm pretty sure he's just trying to compute an angle from a slope. The syntax for accessing the matrix element stored in row A and column B of matrix [C] is as follows:
[C](A,B)
On graphing calculators, remember order of operations. Here's the slope in your expression:
(Y2-Y1)/(X2-X1)
Anyways, to find an angle (in radians or degrees, depending on the mode that your calculator is in) from your matrix, assuming that it's stored in matrix [A]:
tan-1(([A](2,2)-[A](1,2))/([A](2,1)-[A](1,1)))
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-quoted directly from most movies that don't exist (and some that do). |
Vectris
Ultralisk
Posted: 29 May 2008
09:09 GMT
Total Posts: 375 | Like I said I'm not a math genius >.>, but I see it now haveacalc, thanks.
TheRock, I'm assuming that you have a graphing calculator? A TI-83/84 or something? Here's the program for it, very simple but it will do what you wanted.
(Before using the program, all your data must be stored in Matrix A, in the same format as you posted, [point1,x,y]
:ClrHome
:Input "POINT 1:",A
:Input "POINT 2:",B
:Disp tan-1(([A](A,3)-[A](B,3))/([A](A,2)-[A](B,2
And thats it.
If you need help putting it on your calculator just post.
Remember, [A] isn't just typing [ + A + ], its the variable, which can be found by pressing 2nd + x-1 and then pressing enter (which selects Matrix A). |
therock003
Probe
Posted: 29 May 2008
09:35 GMT
Total Posts: 9 | First of all thanx for your partitipation and your interest on my mateer.
Other than that let me answer some of your questions.The matrix size for this particular operation will be 3xn.3 being the columns cause there's only 3 types of input and n will be the number of points i will store on each occasion.
For example if i have to work with 100 points,then of course the size will be 3x100.
Other than that,let me state that havecalc is correct,i want to calculate angles,but directional angles,not slopes.Meaning you have to take the direction of the true north into consideration.
Other than that I and J is the x and y coords of the two points that participate.
For example a direction is formed by two points.Point A and Point B.Xi,Yi are the coords of point A and Yj,Yj coords of point B.
Now the last piece of information is that to calculate the directional angle you calculate the absolute value of the arctan.
a'=arctan|Dx/Dy|
And then id Dx/Dy = +/+ angle = a'
if Dx/Dy = -/+ angle = 200-a'
if Dx/Dy = -/- angle = 200+a'
if Dx/Dy = +/- angle = 400-a'
EDIT:Sorry i see you edited the message after i posted and without me having given the complete picture.I do have a calc ti-89 titanium,and i'm really looking forward to putting it to use.
|
Barrett
Administrator
Posted: 29 May 2008
15:49 GMT
Total Posts: 1676 | Mostly what you're looking for is the syntax on how to create a matrix, modify its contents, size, and read from it. All of that is explained on http://education.ti.com/. Just look for the guide book section.
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-Barrett A |
