title: Interpreting gdb output where FPE is occurring
body: <p>I am using the same instructions as provided in this URL - <a href="https://undo.io/resources/blog-articles/debugging-fortran-code-gdb/" rel="nofollow noreferrer">Debug fortran code with  gdb</a> and I am getting these messages -</p>
  
  <pre><code>Breakpoint 1, psiappsor (omega=1.80999994, 
  pv=&lt;error reading variable: value requires 31250000 bytes, which is more than max-value-size&gt;, 
  psi=&lt;error reading variable: value requires 31250000 bytes, which is more than max-value-size&gt;, nsq=..., rhoref=..., 
  thetatop=&lt;error reading variable: value requires 250000 bytes, which is more than max-value-size&gt;, 
  thetabot=&lt;error reading variable: value requires 250000 bytes, which is more than max-value-size&gt;, thetaref=..., 
  coriol=&lt;error reading variable: value requires 250000 bytes, which is more than max-value-size&gt;, 
  ua=&lt;error reading variable: value requires 125000 bytes, which is more than max-value-size&gt;, 
  ub=&lt;error reading variable: value requires 125000 bytes, which is more than max-value-size&gt;, 
  va=&lt;error reading variable: value requires 125000 bytes, which is more than max-value-size&gt;, 
  vb=&lt;error reading variable: value requires 125000 bytes, which is more than max-value-size&gt;, 
  a=&lt;error reading variable: value requires 31250000 bytes, which is more than max-value-size&gt;, 
  b=&lt;error reading variable: value requires 31250000 bytes, which is more than max-value-size&gt;, 
  c=&lt;error reading variable: value requires 31250000 bytes, which is more than max-value-size&gt;, nx=249, ny=249, nz=124, dx=26437.7188, dy=27813.7012, 
  dz=200.139206) at inv_cart.f:1226
  1226         &gt;              c(i,j,k))+(1.-omega)*psi(i,j,k).
  </code></pre>
  
  <p>Googling these texts or looking up previous SO Q/A's is not helpful at all. I can tell you that a lot of these variables such as pv, psi, thetatop, thetabot, ua,ub,va,vb,a,b,c are being passed in from the calling subroutine. 
  Is that what is causing these messages ? I can post the full code associated with the breakpoint if required. What do these messages mean ?</p>