Small improvements and absolute percent error for the Julia Monte Carlo (#325)

* Print pi estimate.

* Fix percent error calculation.

* Make the percent error always be a positive value, by using the absolute value of a critical calculation step. Also space out the calculation of the error a bit.

Author: june128

contents/monte_carlo_integration/code/julia/monte_carlo.jl

@@ -24,7 +24,8 @@ function monte_carlo(n::Int64)
     #     are only using the upper quadrant and the unit circle, so we can use
     #     4*pi_count/n instead
     pi_estimate = 4*pi_count/n
-    println("Percent error is: ", signif(100*(pi - pi_estimate)/pi, 3), " %")
+    println("The pi estimate is: ", pi_estimate)
+    println("Percent error is: ", signif(100 * abs(pi_estimate - pi) / pi, 3), " %")
 end
 
 monte_carlo(10000000)