Find the Equation for NormalCDF on TI-83/84 Calculator

[sollinton]

Anyone who has a TI-83 or 84 calculator will probably know about the normalcdf(minimum, maximum, mean, std. deviation) command. It is used to find the area under a normal curve between two given points.

My question is; does anyone know the equation that the calculator uses to find this result? I looked in my Probability and Statistics textbook, but could only find the equation for normalpdf:

$$y=\frac{1}{\sigma \sqrt{2\pi}}e^{-\frac{1}{2}(\frac{x-\mu}{\sigma})^2}$$​

If anyone could help me find the equation for normalcdf, I would greatly appreciate it.

Thank you in advance.

 

[yyat]

There you go: http://en.wikipedia.org/wiki/Normal_Distribution#Cumulative_distribution_function"