AMDG Martin Schulz <Martin.Schulz <at> synopsys.com> writes:
It is just the noncontradicted repetition of the "zero-overhead" keyword
over and over again, that irritates me. This indicates that performance is not so unimportant anyhow.
I suppose that the most correct statement is that quantity imposes the same overhead as any wrapper around a plain double. From looking through the assembler output of unit_example_14 it appears that msvc optimized register usage better for double.
in fact the whole example is little meaningfull. It can't prove that the library is fast, nor that it is slow.
I agree. The main thing that the example tests is the compiler's ability to play games. I just tried multiplying 1000 * 1000 matrices together using msvc 8.0 with /Ox /Ot /Ob2 /Oy The results are effectively the same for double and quantity. ublas: double = 16.282 seconds quantity = 16.547 seconds tiled: double = 1.875 seconds quantity = 1.875 seconds
Consequently, I opt against rational exponents, as I consider them to be
an obstacle for such an integration.
How so? At runtime you can use boost::rational In Christ, Steven Watanabe