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Diffstat (limited to 'ext/bigdecimal/lib/newton.rb')
-rw-r--r-- | ext/bigdecimal/lib/newton.rb | 75 |
1 files changed, 0 insertions, 75 deletions
diff --git a/ext/bigdecimal/lib/newton.rb b/ext/bigdecimal/lib/newton.rb deleted file mode 100644 index 67a92474ac..0000000000 --- a/ext/bigdecimal/lib/newton.rb +++ /dev/null @@ -1,75 +0,0 @@ -# -# newton.rb -# -# Solves nonlinear algebraic equation system f = 0 by Newton's method. -# (This program is not dependent on BigDecimal) -# -# To call: -# n = nlsolve(f,x) -# where n is the number of iterations required. -# x is the solution vector. -# f is the object to be solved which must have following methods. -# -# f ... Object to compute Jacobian matrix of the equation systems. -# [Methods required for f] -# f.values(x) returns values of all functions at x. -# f.zero returns 0.0 -# f.one returns 1.0 -# f.two returns 1.0 -# f.ten returns 10.0 -# f.eps convergence criterion -# x ... initial values -# -require "ludcmp" -require "jacobian" - -module Newton - include LUSolve - include Jacobian - - def norm(fv,zero=0.0) - s = zero - n = fv.size - for i in 0...n do - s += fv[i]*fv[i] - end - s - end - - def nlsolve(f,x) - nRetry = 0 - n = x.size - - f0 = f.values(x) - zero = f.zero - one = f.one - two = f.two - p5 = one/two - d = norm(f0,zero) - minfact = f.ten*f.ten*f.ten - minfact = one/minfact - e = f.eps - while d >= e do - nRetry += 1 - # Not yet converged. => Compute Jacobian matrix - dfdx = jacobian(f,f0,x) - # Solve dfdx*dx = -f0 to estimate dx - dx = lusolve(dfdx,f0,ludecomp(dfdx,n,zero,one),zero) - fact = two - xs = x.dup - begin - fact *= p5 - if fact < minfact then - raize "Failed to reduce function values." - end - for i in 0...n do - x[i] = xs[i] - dx[i]*fact - end - f0 = f.values(x) - dn = norm(f0,zero) - end while(dn>=d) - d = dn - end - nRetry - end -end |