title: Mathematica CForm / FortranForm bug?
body: <p>I am trying to output a very complicated matrix (~1.3MB in plain text) from Mathematica to use in a Fortran program. When I do this (via <code>Splice</code>) the resulting matrix is off by ~2% when numerical values are given to the variables. This is a problem since there needs to be an eigenvalue that is exactly zero, and the composition of the eigenvectors needs to be exactly correct.</p>
  
  <p>I've done all the usual due diligence regarding precision, correct variables, proper diagonalization code, etc. and It came down to either Fortran itself being unable to cope with such a large matrix or Mathematica messing up the FortranForm output.</p>
  
  <p>So I made Mathematica give me the CForm of the matrix and tried that. It was also ~2% off from what it should be, more astoundingly, it was the same (within machine precision) as the FortranForm matrix!</p>
  
  <p>Has anyone come into contact with this kind of problem? Do you have any idea what might cause it? I dread the need to go through 25000 lines of Mathematica formatted Fortran code to figure this one out.</p>
  
  <p>EDIT: The matrix in question is complicated, not large. It is only 6x6 but each element is individually algebraically very messy including trigonometric functions, logarithms, and various roots and powers.</p>
  
  <p>The <a href="http://pastebin.com/wYyemZUN" rel="nofollow">Plaintext</a> of the (1,1) element of our matrix, the <a href="http://pastebin.com/tu7tEmJE" rel="nofollow">C code</a>, and the <a href="http://pastebin.com/r5Vw2U5b" rel="nofollow">Fortran code</a>. Sane parameter values are: 0 &lt; lambda, kappa, Y*** &lt; 1; all others between 100 and 1000.  </p>