On Saturday, 21 October 2017 at 20:17:12 UTC, NX wrote:
I was working on some sort of math library for use in graphical
computing and I wrote something like this:
const float PiOver2 = (atan(1.0) * 4) / 2;
Interestingly enough, I realized that atan() returns double (in
this case) but wait, it's assigned to a float variable!
Compiler didn't even emit warnings, let alone errors.
I see no reason as to why would this be legal in this century,
especially in D.
So can someone tell me what's the argument against this?
Why type conversions differ between integral and floating types?
Why can't I assign a long to an int but it's fine when
assigning double to float?
I think this is a serious topic and needs clarification.
I think that the rationale for allowing that is that you can feed
the FPU with high precision values to get a better internal
accuracy (temp values stored in ST0-ST7). At the end, even if
there's a truncation the result is more accurate that if you
would have feed the FPU with parameters of the same size as the
result.
