Mercurial > octave
comparison libinterp/corefcn/rand.cc @ 17258:213ee68b59da
Handle out-of-range values consistently when initializing random number generator.
* oct-rand.cc: New function double2uint32(). It normalizes a finite double by
taking it modulo 2^32, such that the result is in [0, 2^32). Nonfinites give
zero as result. This prevents compiler-dependent casting of a double whose
truncated value cannot be represented in a uint32_t.
* rand.cc: Add %!test block to verify behavior.
| author | Philipp Kutin <philipp.kutin@gmail.com> |
|---|---|
| date | Thu, 15 Aug 2013 20:14:30 +0200 |
| parents | 2fc554ffbc28 |
| children | bc924baa2c4e |
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| 17257:ce55a8575874 | 17258:213ee68b59da |
|---|---|
| 531 %! assert (skewness (x), 0, 0.012); | 531 %! assert (skewness (x), 0, 0.012); |
| 532 %! assert (kurtosis (x), -6/5, 0.0094); | 532 %! assert (kurtosis (x), -6/5, 0.0094); |
| 533 %! endif | 533 %! endif |
| 534 */ | 534 */ |
| 535 | 535 |
| 536 /* | |
| 537 %!# Test out-of-range values as rand() seeds. See oct-rand.cc: double2uint32(). | |
| 538 %!function v = __rand_sample__ (initval) | |
| 539 %! rand ("state", initval); | |
| 540 %! v = rand (1, 6); | |
| 541 %!endfunction | |
| 542 %! | |
| 543 %!assert (__rand_sample__ (0), __rand_sample__ (2^32)) | |
| 544 %!assert (__rand_sample__ (-2), __rand_sample__ (2^32-2)) | |
| 545 %!assert (__rand_sample__ (Inf), __rand_sample__ (NaN)) | |
| 546 %!assert (! isequal (__rand_sample__ (-1), __rand_sample__ (-2))) | |
| 547 */ | |
| 548 | |
| 536 static std::string current_distribution = octave_rand::distribution (); | 549 static std::string current_distribution = octave_rand::distribution (); |
| 537 | 550 |
| 538 DEFUN (randn, args, , | 551 DEFUN (randn, args, , |
| 539 "-*- texinfo -*-\n\ | 552 "-*- texinfo -*-\n\ |
| 540 @deftypefn {Built-in Function} {} randn (@var{n})\n\ | 553 @deftypefn {Built-in Function} {} randn (@var{n})\n\ |