title: What does "real*8" mean?
body: <p>The manual of a program written in Fortran 90 says, "All real variables and parameters are specified in 64-bit precision (i.e. <code>real*8</code>)."</p>
  
  <p>According to <a href="http://en.wikipedia.org/wiki/Single_precision" rel="noreferrer">Wikipedia</a>, single precision corresponds to 32-bit precision, whereas double precision corresponds to 64-bit precision, so apparently the program uses double precision.  </p>
  
  <p>But what does <code>real*8</code> mean?  </p>
  
  <p>I thought that the <code>8</code> meant that 8 digits follow the decimal point. However, <a href="http://en.wikipedia.org/wiki/Single_precision" rel="noreferrer">Wikipedia</a> seems to say that single precision typically provides 6-9 digits whereas <a href="http://en.wikipedia.org/wiki/Double-precision_floating-point_format" rel="noreferrer">double precision</a> typically provides 15-17 digits. Does this mean that the statement "64-bit precision" is inconsistent with <code>real*8</code>? </p>