Float Algorithm Performance

Note that these tests are carefully designed to test performance of the underlying algorithms and not memory allocation or variable copying. As usual, performance results should be taken with a healthy dose of scepticism, and real-world performance may vary widely depending upon the specifics of the program. In each table relative times are given first, with the best performer given a score of 1. Total actual times are given in brackets, measured in seconds for 500000 operations.

Table 1.10. Operator +

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.0575156s)	1 (0.0740086s)	1 (0.219073s)
gmp_float	2.45065 (0.14095s)	2.01398 (0.149052s)	1.09608 (0.240122s)
mpfr_float	2.6001 (0.149546s)	2.12079 (0.156957s)	1.09078 (0.23896s)

Table 1.11. Operator +(int)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1.46115 (0.0855392s)	2.60353 (0.114398s)	3.62562 (0.264905s)
gmp_float	1 (0.0585424s)	1 (0.0439398s)	1 (0.0730648s)
mpfr_float	2.40441 (0.14076s)	3.2877 (0.144461s)	2.40379 (0.175632s)

Table 1.12. Operator +(unsigned long long)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.118146s)	1 (0.144714s)	1 (0.315639s)
gmp_float	4.5555 (0.538213s)	3.83096 (0.554395s)	1.95079 (0.615745s)
mpfr_float	5.74477 (0.678719s)	4.85295 (0.702291s)	2.70354 (0.853342s)

Table 1.13. Operator +=(unsigned long long)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.101188s)	1 (0.122394s)	1 (0.251975s)
gmp_float	5.199 (0.526079s)	4.39327 (0.537712s)	2.42151 (0.610159s)
mpfr_float	6.08318 (0.615547s)	5.18525 (0.634645s)	3.1022 (0.781677s)

Table 1.14. Operator -

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.0895163s)	1 (0.129248s)	1.5088 (0.374512s)
gmp_float	1.72566 (0.154474s)	1.22567 (0.158415s)	1 (0.248219s)
mpfr_float	1.83764 (0.164499s)	1.34284 (0.173559s)	1.00226 (0.248781s)

Table 1.15. Operator -(int)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.105285s)	1 (0.142741s)	1 (0.278718s)
gmp_float	2.34437 (0.246828s)	1.28814 (0.183871s)	1.00731 (0.280754s)
mpfr_float	2.8032 (0.295136s)	2.09178 (0.298582s)	1.25213 (0.34899s)

Table 1.16. Operator -(unsigned long long)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.13719s)	1 (0.184428s)	1 (0.344212s)
gmp_float	4.0804 (0.559791s)	3.06776 (0.565781s)	2.07736 (0.715053s)
mpfr_float	5.10114 (0.699828s)	3.88684 (0.716843s)	2.50074 (0.860784s)

Table 1.17. Operator -=(unsigned long long)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.100984s)	1 (0.123148s)	1 (0.246181s)
gmp_float	5.68353 (0.573944s)	4.68636 (0.577116s)	2.6958 (0.663655s)
mpfr_float	6.19738 (0.625834s)	5.18544 (0.638577s)	3.18738 (0.784673s)

Table 1.18. Operator *

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1.03667 (0.284251s)	1.30576 (0.536527s)	1.44686 (4.81057s)
gmp_float	1 (0.274196s)	1 (0.410891s)	1 (3.32484s)
mpfr_float	1.24537 (0.341477s)	1.15785 (0.475749s)	1.1796 (3.92199s)

Table 1.19. Operator *(int)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	3.97453 (0.240262s)	9.91222 (0.463473s)	50.7926 (4.36527s)
gmp_float	1 (0.0604505s)	1 (0.0467577s)	1 (0.0859431s)
mpfr_float	2.56974 (0.155342s)	3.56312 (0.166603s)	3.22964 (0.277565s)

Table 1.20. Operator *(unsigned long long)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.331877s)	1.01058 (0.586122s)	6.688 (4.7931s)
gmp_float	1.72433 (0.572266s)	1 (0.579987s)	1 (0.716672s)
mpfr_float	2.5553 (0.848047s)	1.74987 (1.0149s)	1.80403 (1.2929s)

Table 1.21. Operator *=(unsigned long long)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.321397s)	1.00772 (0.574887s)	6.65946 (4.7468s)
gmp_float	1.77419 (0.570218s)	1 (0.570482s)	1 (0.712791s)
mpfr_float	2.62172 (0.842611s)	1.77691 (1.01369s)	1.77511 (1.26528s)

Table 1.22. Operator /

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	2.96096 (4.00777s)	4.53244 (7.86435s)	6.11936 (51.5509s)
gmp_float	1 (1.35354s)	1 (1.73512s)	1 (8.42422s)
mpfr_float	1.30002 (1.75963s)	1.39045 (2.41261s)	1.66762 (14.0484s)

Table 1.23. Operator /(int)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	8.60726 (1.8181s)	15.4122 (3.67479s)	34.5119 (24.729s)
gmp_float	1.24394 (0.262756s)	1 (0.238433s)	1 (0.716536s)
mpfr_float	1 (0.211229s)	1.12178 (0.26747s)	1.02237 (0.732562s)

Table 1.24. Operator /(unsigned long long)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	2.10976 (1.97569s)	3.73601 (3.9133s)	11.3085 (25.4533s)
gmp_float	1 (0.936452s)	1 (1.04746s)	1 (2.25081s)
mpfr_float	1.3423 (1.257s)	1.51575 (1.58768s)	3.31513 (7.46175s)

Table 1.25. Operator /=(unsigned long long)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	2.17401 (1.96883s)	3.79591 (3.8965s)	11.2328 (25.2606s)
gmp_float	1 (0.905621s)	1 (1.0265s)	1 (2.24882s)
mpfr_float	1.37953 (1.24933s)	1.53073 (1.57129s)	3.30546 (7.43339s)

Table 1.26. Operator construct

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.00929804s)	1 (0.0268321s)	1 (0.0310685s)
gmp_float	30.8781 (0.287106s)	7.59969 (0.203916s)	6.51873 (0.202527s)
mpfr_float	23.5296 (0.218779s)	8.11058 (0.217624s)	7.16325 (0.222552s)

Table 1.27. Operator construct(unsigned)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.0603971s)	1 (0.0735485s)	1 (0.116464s)
gmp_float	3.91573 (0.236498s)	2.88171 (0.211945s)	1.81075 (0.210887s)
mpfr_float	4.90052 (0.295977s)	4.01118 (0.295017s)	2.62005 (0.305141s)

Table 1.28. Operator construct(unsigned long long)

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	1 (0.0610288s)	1 (0.0759005s)	1 (0.118511s)
gmp_float	8.26247 (0.504249s)	6.69042 (0.507806s)	4.32819 (0.51294s)
mpfr_float	10.1593 (0.620013s)	8.45884 (0.64203s)	5.51472 (0.653557s)

Table 1.29. Operator str

Backend	50 Bits	100 Bits	500 Bits
cpp_dec_float	2.95848 (0.0223061s)	3.33461 (0.033471s)	3.0159 (0.132732s)
gmp_float	1 (0.00753971s)	1 (0.0100374s)	1 (0.0440106s)
mpfr_float	1.25424 (0.00945658s)	1.24943 (0.012541s)	1.09428 (0.0481601s)

Test code was compiled with Microsoft Visual Studio 2010 with all optimisations turned on (/Ox), and used MPIR-2.3.0 and MPFR-3.0.0. The tests were run on 32-bit Windows Vista machine.