Re: Looking for Ada Technique Name and References

[tmoran@bix.com]

>Why is this obfuscated? It does Transpose (E) * F. The * operator does
>multiplication.  Transpose does invert the array, it just does so by
>redefining it instead of moving stuff around in memory. It's not the
  Transpose does not invert the array.  It tells the compiler to use a
different definition of "*".
  Suppose the body of the Matrix."*" routine was re-written, say to take
advantage of new vector arithmetic hardware or to fix an error.
"Transpose (E) * F" would be no faster, and no more correct, since it
actually calls a different "*" function entirely.
  It looks like "Transpose" is doing something to E, but instead it's
modifying "*".  Granted this seems like a useful little white lie,
but tricky code makes me uncomfortable.  The usual recommendation for
tricky, but useful, code is to comment thoroughly.  But compare
X := Transpose(E) * F; -- use the Transpose_Left_And_Multiply function
to
X := TLM(E, F); -- X := Transpose(E) * F;

  Of course if you are trying to save the time of copying an array,
you surely will use procedures, rather than array-returning functions,
anyway.