diff options
| -rw-r--r-- | builtin/common/misc_helpers.lua | 14 | ||||
| -rw-r--r-- | doc/lua_api.txt | 1 |
2 files changed, 15 insertions, 0 deletions
diff --git a/builtin/common/misc_helpers.lua b/builtin/common/misc_helpers.lua index e250b0ed1..25632b4ca 100644 --- a/builtin/common/misc_helpers.lua +++ b/builtin/common/misc_helpers.lua @@ -244,6 +244,20 @@ function math.sign(x, tolerance) end -------------------------------------------------------------------------------- +function math.factorial(x) + assert(x % 1 == 0 and x >= 0, "factorial expects a non-negative integer") + if x >= 171 then + -- 171! is greater than the biggest double, no need to calculate + return math.huge + end + local v = 1 + for k = 2, x do + v = v * k + end + return v +end + +-------------------------------------------------------------------------------- function get_last_folder(text,count) local parts = text:split(DIR_DELIM) diff --git a/doc/lua_api.txt b/doc/lua_api.txt index 05ea6b4bc..593ab50dd 100644 --- a/doc/lua_api.txt +++ b/doc/lua_api.txt @@ -2378,6 +2378,7 @@ Helper functions * tolerance: number, default: `0.0` * If the absolute value of `x` is within the `tolerance` or `x` is NaN, `0` is returned. +* `math.factorial(x)`: returns the factorial of `x` * `string.split(str, separator, include_empty, max_splits, sep_is_pattern)` * `separator`: string, default: `","` * `include_empty`: boolean, default: `false` |