General info on 48/49/50 ROM entry points

[DavidM]

(12-31-2017 01:38 PM)grsbanks Wrote:  

(12-30-2017 04:52 PM)DavidM Wrote:  Keep in mind that most internal numerical functions (as opposed to symbolic) are written for extended reals instead of standard reals.

This is an interesting point. I'll run some benchmarks on this to see if there's a significant difference in execution times between working with standard reals throughout on the one hand and working with extended reals but converting to/from standard reals when needed.

I haven't compared the results in a while, but I seem to recall that there isn't a significant difference in the speed of many standard vs. extended numerical functions. I'd guess this is due to the fact that the conversions to/from extended are relatively quick when compared to the actual processing of the numerical function itself, which is the same code in both cases. My guess is that you'll find a "pure extended" approach only very slightly faster than a "pure standard" one. It may also depend on the specific functions that you test, since the conversion time as a percentage of total time would be larger for the faster commands (eg. +/- vs. TAN/SIN).

The upside to this is that there's usually no performance penalty for using the extended real functions in SysRPL programs. You just have to remember to do the conversions. While an extended real on the stack simply looks like a longer-than-normal real in scientific notation, there's not much you can do with them outside of a custom program (or specific SYSEVALs).