• C

inverse matrix

how can I get the inverse of a N x N matrix I need this code ASAP please very quick
latinoAsked:
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RONSLOWConnect With a Mentor Commented:
Why the reject ???  
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latinoAuthor Commented:
I Need this answer as soon as posible !!!!!!!!
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rbrCommented:
It depends on the size an shape of your matrix. If you need different algorithmen look for the book Numerical Recipies in C.

Online source code for this book at
http://
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rbrCommented:
Sorry i forgot the WWW-adress:
http://cfatab.havard.edu/nr/nronline.html
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latinoAuthor Commented:
http:// what???? there is no any answer, If please you can help me with the code I'll greatly appreciate it!!!!!!!!!

Ok let's say it's a 10 x 10 matrix

ASAP PLEASE
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latinoAuthor Commented:
This didn't help cause all I need is the code in that URL there is nothing about what I need

What if is a 10 x 10 matrix and I wanna find the inverse

PLEASE ASAP
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latinoAuthor Commented:
Still wating if EXPERTS can strike I'm here
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latinoAuthor Commented:
Still wating if EXPERTS can strike I'm here
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latinoAuthor Commented:
Godness Experts I really need this code I'll greatly appreciate
your assistance!!!!!!!!!!!!!!!!
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RONSLOWCommented:
here is 4x4 ... I'm looking for more for you...

From: gmt@aviator.cis.ufl.edu (Gary McTaggart)
Newsgroups: comp.graphics.algorithms
Subject: Re: Request: Inverse of a 4x4 matrix algorithm
Date: 21 May 1994 20:44:04 GMT
Mike Matsel (matsel@cs.uoregon.edu) wrote:

Does anyone have C code, or at least some psuedo-code for the finding the inverse of a 4 x 4 matrix? Its for a ray tracer. Thanks!
In a lot of cases in graphics, you will be strictly dealing with affine transforms. (My cheesy non-definition of affine is that you are only dealing with translations, rotations, and scaling. . .no shearing or perspective projection.) If this is the case, then you can use the following to find the inverse:


--------------------------------------------------------------------------------


// (Note that a Matrix is:
//   typedef float Matrix[4][4];
//
// Generally speaking, a matrix doesn't need to be bigger than 4x3, but
// since this code is to work with GL and it uses 4x4 matrices. . .

// Find the inverse of a matrix that is made up of only scales, rotations,
// and translations.
void MatrixAffineInverse( Matrix m, Matrix result )
{
  float Tx, Ty, Tz;

  // The rotational part of the matrix is simply the transpose of the
  // original matrix.
  result[0][0] = m[0][0];
  result[1][0] = m[0][1];
  result[2][0] = m[0][2];

  result[0][1] = m[1][0];
  result[1][1] = m[1][1];
  result[2][1] = m[1][2];

  result[0][2] = m[2][0];
  result[1][2] = m[2][1];
  result[2][2] = m[2][2];
 
  // The right column vector of the matrix should always be [ 0 0 0 1 ]
  // In most cases. . . you don't need this column at all because it'll
  // never be used in the program, but since this code is used with GL
  // and it does consider this column, it is here.
  result[0][3] = result[1][3] = result[2][3] = 0;
  result[3][3] = 1;

  // The translation components of the original matrix.
  Tx = m[3][0];
  Ty = m[3][1];
  Tz = m[3][2];
 
  // Rresult = -(Tm * Rm) to get the translation part of the inverse
  result[3][0] = -( m[0][0] * Tx + m[0][1] * Ty + m[0][2] * Tz );
  result[3][1] = -( m[1][0] * Tx + m[1][1] * Ty + m[1][2] * Tz );
  result[3][2] = -( m[2][0] * Tx + m[2][1] * Ty + m[2][2] * Tz );
}

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RONSLOWCommented:
Here is another at http://irecall.com/vve/matrix.c


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latinoAuthor Commented:
I can still wait for this a little bit more
thanks Ronslow
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kellyjjCommented:
Sounds like a homework assignment?  I have to ask you... Do you know how to get the inverse of a matrix by hand??  If you can't do it by hand then you really won't be able to understand or even write a program to do it for you.  

If you do know how to get the inverse by hand the just write code to do what you would do.  I know that it won't be the best code, but it will be a good starting point.
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latinoAuthor Commented:
you are right kelly it's a homework but I know how to get it by hand but this code should be able to get the inverse of a matrix bigger than a 4 X 4 and that's where I fall dowm! but I'll keep trying and see what I come up with

Thanks anyway
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RONSLOWCommented:
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hbadrCommented:
do you still want the code ??
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latinoAuthor Commented:
I do habdr!!! thanks
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RONSLOWCommented:
Why the reject ???
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latinoAuthor Commented:
Thanks Ronslow
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