title: Converting hexadecimal to IEEE754 hexadecimal representation
body: <p>What would be the best way to convert from hexadecimal textual representation to it's IEEE754 representation in double precision (that would result in minimal rounding)?</p>
  <p>For example, converting:</p>
  <p><code>-0x1.f8b791cafcdefp+4</code>  to  <code>C03F8B791CAFA2C0</code></p>
  <p>My current method is to convert from hexadecimal to a <code>double</code>, then convert this to IEEE754 representation, but this obviously involves dubious levels of rounding.</p>