Lua 5.05.0

1 files changed, 7 insertions, 9 deletions

diff --git a/test/bisect.lua b/test/bisect.lua
index 9e1d8f70..f91e69bf 100644
--- a/test/bisect.lua
+++ b/test/bisect.lua
@@ -1,25 +1,23 @@
 -- bisection method for solving non-linear equations
 
+delta=1e-6	-- tolerance
+
 function bisect(f,a,b,fa,fb)
- write(n," a=",a," fa=",fa," b=",b," fb=",fb,"\n")
  local c=(a+b)/2
- if c==a or c==b then return c end
- if abs(a-b)<delta then return c end
+ io.write(n," c=",c," a=",a," b=",b,"\n")
+ if c==a or c==b or math.abs(a-b)<delta then return c,b-a end
  n=n+1
  local fc=f(c)
  if fa*fc<0 then return bisect(f,a,c,fa,fc) else return bisect(f,c,b,fc,fb) end
 end
 
--- find root of f in the inverval [a,b]. bisection needs that f(a)*f(b)<0
+-- find root of f in the inverval [a,b]. needs f(a)*f(b)<0
 function solve(f,a,b)
- delta=1e-9	-- tolerance
  n=0
- local z=bisect(f,a,b,f(a),f(b))
- write(format("after %d steps, root is %.10g, f=%g\n",n,z,f(z)))
+ local z,e=bisect(f,a,b,f(a),f(b))
+ io.write(string.format("after %d steps, root is %.17g with error %.1e, f=%.1e\n",n,z,e,f(z)))
 end
 
--- an example
-
 -- our function
 function f(x)
  return x*x*x-x-1