Exponential Integral Ei x actual ei(x) 0.10 -1.622810 -1.622813 0.20 -0.821761 -0.821761 0.30 -0.302669 -0.302668 0.40 0.104768 0.104765 0.50 0.454220 0.454220 0.60 0.769881 0.769881 0.70 1.064910 1.064907 0.80 1.347400 1.347397 0.90 1.622810 1.622812 2.20 5.732610 5.732615 2.40 6.600670 6.600670 3.50 13.925400 13.925355 3.90 18.315701 18.315716 5.00 40.185299 40.185276 5.40 54.193501 54.193478 12.50 23565.099609 23565.113281 13.00 37197.699219 37197.683594 13.50 58827.000000 58826.960938 14.00 93193.000000 93192.507813 14.50 147866.000000 147866.187500 15.00 234955.000000 234955.828125