
Topic review (newest first)
 kylekatarn
 20050905 01:57:44
solving 20 equations to 20 variables can be done with something as simple as a Ti84 calculator
just enter the coefs into a matrix and then use the command rref( 'matrix name' ) to get the solution matrix
rref  reduced row echelon form.
 MathsIsFun
 20050904 20:46:59
Ahhh, good question. I am not a statistics guru, perhaps another member has more knowledge on this than I do.
I can tell you that in practice most people use statistical analysis software for this job. A good program will give you many different ways to analyze the data.
You see, you may want to look at different aspects of the data, for example how each component affects the result (for example "a" and "c" might be very influential) (I seem to recall Analysis of Variance is useful here, look for the term ANOVA or MANOVA)
But if you just want to do a simple job, put the data into Excel and play with it!
 oechel
 20050904 19:41:44
The data comes indeed from a survey Then what kind of statistical analysis method should I use?
 MathsIsFun
 20050904 17:51:04
Oh, got it the wrong way around LOL!
OK, I need to know a little more. Is the data "soft" or "hard" (my words), in other words, is it
A) like a survey where the data is not exact, or B) is each one an actual equation (ie, if you have values for a to e then they will always get the results shown)
If it is A) then it is Statistics, in other words something like "people who have 12 of a, and 26 of b ... have a satisfaction level of 9". And in Statistics there are many different ways of solving the "best fit", depending on how the data was collected and what results you want.
If it is B), then just pick any 5 and solve them, the rest should also be right
 oechel
 20050904 17:32:58
Thanks, but the problem is more complicated. Each parameter is a measured value, the result is a rating from 010 I'm wondering if there exists a program to solve this kind of matrix
As an example: 12a + 26b  36c + 44d + 3e = 9 7a + 99b + 255c + 0d  55e = 3 56a  44b + 92c + 66d + 22e = 5 2a + 69b + 55c + 37d + 36e = 10 5a + 68b  44c + 87d + 33e = 1 99a + 51b + 33c + 5d  48e = 6 ... and so on, totally 20 equations
 MathsIsFun
 20050904 09:02:50
You should be able to reduce the number of equations, let's try an example:
a+b=2c ab=c
That has 3 unknowns but only 2 equations, so let's do our best to solve it:
Combine the two: a+b = 2c = 2(ab) Therefore: a+b = 2a  2b Subtract a from both sides: b=a2b Add 2b to both sides: 3b = a
So we end up reducing this to:
a = 3b
So, we have a range of solutions.
For example: b=1, a=3b=3, a+b=4, ab=2, c=2 Or: b=2, a=3b=6, a+b=8, ab=4, c=4 etc ...
 oechel
 20050904 05:54:56
Does somebody have a sollution to solve equations which have more equations then parameters
