require 'bigdecimal'
class ExtrFinder
    def initialize(f,a,b,eps, fprime)
        @f = f
        @a = a
        @b = b
        @eps = eps
        @fprime = fprime
    end
 
    def dixitom
        @iter = 0
        while (@b - @a) > 2 *  @eps
            @iter +=1
            @c = (@a + @b)/BigDecimal("2.0")
            if @f.call(@a) * @f.call(@c) > 0
                @a = @c
            else
                @b = @c
            end
        end
    end
 
     def newton(x0)
        @iter = 0
	@x0 = x0
	@x1 = x0
        begin
	    @x0 = @x1
            @iter += 1
            @y = @f.call(@x0)
            @yprime = @fprime.call(@x0)
            @x1 = @x0 - @y/@yprime           
        end while @f.call(@x1) * @f.call(@x1 + @eps * self.sign(@f.call(@x1) - @f.call(@x0))) < 0
    end 
    
    def sign(x)
	    #print "x in sign: ", x, "\n"
	    #print "sign: ", x/x.abs, "\n"
	    if x == 0
		    return 0
 	    else    return x/x.abs
	    end    
		 
    end
 
    def printresultd
        print "dih: ", "iter: ", @iter," zer:" , ((@a + @b)/2.0), "\n"
    end
    def printresultn
        print "new: ", "iter: ", @iter," zer:" ,( @x1 + @eps * self.sign(@f.call(@x1) - @f.call(@x0))/2.0 ) , "\n"
    end
end
func = Proc.new {|x| (x - 1)*(x - 2)*(x - 3)}
fprime = Proc.new {|x| 3 * x * x - 12 * x + 11}
counter = ExtrFinder.new(func, BigDecimal("0.5"), BigDecimal("1.5"), BigDecimal("0.1"),fprime)
counter.dixitom
counter.printresultd
counter = ExtrFinder.new(func, BigDecimal("1.5"), BigDecimal("2.5"), BigDecimal("0.1"),fprime)
counter.dixitom
counter.printresultd
counter = ExtrFinder.new(func, BigDecimal("2.5"), BigDecimal("3.5"), BigDecimal("0.1"),fprime)
counter.dixitom
counter.printresultd
counter = ExtrFinder.new(func, BigDecimal("0.5"), BigDecimal("1.5"), BigDecimal("0.1"),fprime)
counter.newton(0.9)
counter.printresultn
counter = ExtrFinder.new(func, BigDecimal("1.5"), BigDecimal("2.5"), BigDecimal("0.1"),fprime)
counter.newton(1.9)
counter.printresultn
counter = ExtrFinder.new(func, BigDecimal("2.5"), BigDecimal("3.5"), BigDecimal("0.1"),fprime)
counter.newton(2.9)
counter.printresultn