What is the standard (or best supported) big number (arbitrary precision) library for Lua?

math lua precision bignum
Jon Ericson picture Jon Ericson · Nov 14, 2008 · Viewed 8.7k times · Source

I'm working with large numbers that I can't have rounded off. Using Lua's standard math library, there seem to be no convenient way to preserve precision past some internal limit. I also see there are several libraries that can be loaded to work with big numbers:

  1. http://oss.digirati.com.br/luabignum/
  2. http://www.tc.umn.edu/~ringx004/mapm-main.html
  3. http://lua-users.org/lists/lua-l/2002-02/msg00312.html (might be identical to #2)
  4. http://www.gammon.com.au/scripts/doc.php?general=lua_bc (but I can't find any source)

Further, there are many libraries in C that could be called from Lua, if the bindings where established.

Have you had any experience with one or more of these libraries?

Answer

lhf picture lhf · May 14, 2009

Using lbc instead of lmapm would be easier because lbc is self-contained.

local bc = require"bc"
s=bc.pow(2,1000):tostring()
z=0
for i=1,#s do
        z=z+s:byte(i)-("0"):byte(1)
end
print(z)

Related questions

Sort points in clockwise order?

Given an array of x,y points, how do I sort the points of this array in clockwise order (around their overall average center point)? My goal is to pass the points to a line-creation function to end up with …

Read More
Lua replacement for the % operator

I want to check, if a number is divisible by another number: for i = 1, 100 do if i % 2 == 0 then print( i .. " is divisible.") end end This should work without any problems, but with the Lua in my server the script doesn't …

Read More
In Lua, how can I tell if a number divides evenly into another number?

In Lua, how can I tell if a number divides evenly into another number? i.e with no remainder? I'm just looking for a boolean true or false. 12/6 = 2 (true) 18/6 = 3 (true) 20/6 = 3.(3) (false)

Read More