Solving system of equations

[eriku]

I need to solve a system of eq:s with 6 unknown on line (in a trim routine for a simulation model). Do you happen to know where I can find a good function that does that?
/ Erik

[bonski]

I need to solve a system of eq:s with 6 unknown on line (in a trim routine for a simulation model). Do you happen to know where I can find a good function that does that?
/ Erik

hello erik,

what equation? can you show us what's the formula?

^__^

[eriku]

hello erik,

what equation? can you show us what's the formula?

^__^

A linear system of eq:s, i.e.
Ax + b=0
where A is a n*n matrix, x is a n-dimensional vector of unknown and b is a n-dim. constant vector.
n=6 in the actual case, could be 7 or more tomorrow.

A mathematics library in PHP (something like LAPACK in Fortran) is too much to wish for, but maybe someone has translated something ...?

/ Erik

[bonski]

A linear system of eq:s, i.e.
Ax + b=0
where A is a n*n matrix, x is a n-dimensional vector of unknown and b is a n-dim. constant vector.
n=6 in the actual case, could be 7 or more tomorrow.

A mathematics library in PHP (something like LAPACK in Fortran) is too much to wish for, but maybe someone has translated something ...?

/ Erik

ok.. im not really sure bout this.. but i'll try to interpret if it is correct..

Ax + b = 0;

A = n * n;
and the value of n = 6; right? what do you mean 'could be 7 or more tomorrow'?

x = ?;
and
b = n; b is n-dim so b has to be equal to n, is that right?

think i had to review math first.. hahaha.. i think all we need about this are values.. then you can get the unknown.. hmmmm

[eriku]

ok.. im not really sure bout this.. but i'll try to interpret if it is correct..

Ax + b = 0;

A = n * n;
and the value of n = 6; right? what do you mean 'could be 7 or more tomorrow'?

x = ?;
and
b = n; b is n-dim so b has to be equal to n, is that right?

think i had to review math first.. hahaha.. i think all we need about this are values.. then you can get the unknown.. hmmmm

No, A is a matrix with 6 rows and 6 columns!
/ Erik

[shoonya]

i can recall cramer's rule and similar methods to solve these equations

shoonya

[shoonya]

http://www.purplemath.com/modules/cramers.htm

i got the link
i guess coding it wont be a problem for you

shoonya

[eriku]

http://www.purplemath.com/modules/cramers.htm
i got the link
i guess coding it wont be a problem for you

shoonya

Thank you shoonya!
A generalisation like expanding to 6*6 or more is not quite trivial, so I was (still am) hoping to find something already tested and cleared. But if nothing turns up, I guess I have to go the hard way via Cramer's rule. Or maybe translate some suitable routines from LAPACK (probably better).

/ Erik

[shoonya]

what is this LAPACK ?

shoonya

[eriku]

what is this LAPACK ?

shoonya

http://www.netlib.org/lapack/index.html
/ Erik