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authorantirez <antirez@gmail.com>2011-04-30 16:15:30 +0200
committerantirez <antirez@gmail.com>2011-05-25 12:32:43 +0200
commit21d3294c7013a4385aebd84436394bb58e273093 (patch)
tree865bb98821fbc2c0d0fa618bf6297efd4c2cefef /deps/lua/test/bisect.lua
parentefc3408748061a08ec5ff18e392c30f31f5094a2 (diff)
downloadredis-21d3294c7013a4385aebd84436394bb58e273093.tar.gz
makefile adapted to link against lua lib and to pass the 32bit flag to Lua building system
Diffstat (limited to 'deps/lua/test/bisect.lua')
-rw-r--r--deps/lua/test/bisect.lua27
1 files changed, 27 insertions, 0 deletions
diff --git a/deps/lua/test/bisect.lua b/deps/lua/test/bisect.lua
new file mode 100644
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+++ b/deps/lua/test/bisect.lua
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+-- bisection method for solving non-linear equations
+
+delta=1e-6 -- tolerance
+
+function bisect(f,a,b,fa,fb)
+ local c=(a+b)/2
+ 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]. needs f(a)*f(b)<0
+function solve(f,a,b)
+ n=0
+ 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
+
+-- our function
+function f(x)
+ return x*x*x-x-1
+end
+
+-- find zero in [1,2]
+solve(f,1,2)