Note that some authors e g whittaker and watson 1990 p.
													
																	Error function math. 
									
	
		
	
																	In statistics a common example is the difference between the mean of an entire population and the mean of a sample drawn from that population. 
																	Error in applied mathematics the difference between a true value and an estimate or approximation of that value. 
																	341 define without the leading factor of. 
																	Erf is implemented in the wolfram language as erf z a two argument form giving is also implemented as erf z0 z1. 
															
													
									
	
		
	
																	Function in mathematics an expression rule or law that defines a relationship between one variable the independent variable and another variable the dependent variable. 
																	X erf x 1 erf x 0. 
																	Input specified as a symbolic number variable expression or function or as a vector or matrix of symbolic numbers variables expressions or functions. 
																	Functions are ubiquitous in mathematics and are essential for formulating physical relationships in the sciences.