gistfile1.rb

# gradient descent in ruby

def find_min(x_old, x_new, precision, eps, &block)
  while (x_new - x_old).abs > precision
    x_old = x_new
    tmp = yield x_new
    x_new = x_new - eps * tmp
  end
  x_new
end

# usage: the block contains the derivative of f(x)=x^4-3x^3+2
# find_min(0, 0.1, 0.00001, 0.01) { |x| (4 * (x**3)) - (9 * (x**2)) }