Class: RootSolver::Newton

Inherits:
Object
  • Object
show all
Defined in:
lib/root_solver.rb

Instance Method Summary collapse

Constructor Details

#initialize(f, x0 = 0, tol = 0.01, n = 10, eps = 0.001) ⇒ Newton

Returns a new instance of Newton.



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# File 'lib/root_solver.rb', line 5

def initialize(f, x0 = 0, tol = 0.01, n = 10, eps = 0.001)
  @f   = f
  @x0  = x0
  @tol = tol
  @n   = n
  @eps = eps
end

Instance Method Details

#solve(f = @f, x0 = @x0, tol = @tol, n = @n, eps = @eps) ⇒ Object

Raises:



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# File 'lib/root_solver.rb', line 13

def solve(f = @f, x0 = @x0, tol = @tol, n = @n, eps = @eps)
  y0 = f.call(x0)
  y_prime = (f.call(x0 + eps) - y0) / eps

  raise NonconvergenceError.new if y_prime.abs < tol

  x = x0 - y0 / y_prime
  y = f.call(x)
  if y.abs < tol #successfully found root
    x
  elsif n <= 0 #solver not within threshold after n iterations.
    x
  else
    solve(f, x, tol, n - 1, eps)
  end
end