ERF Function

Returns the value of the (normal) error function.

Categories:	Mathematical
Categories:	Arithmetic
Returned data type:	DOUBLE

Syntax

Arguments

Details

Example

Syntax

ERF(expression)

Arguments

expression

specifies any valid expression that evaluates to a numeric value.

Data type	DOUBLE
See	<sql-expression>
See	FedSQL Expressions

Details

The ERF function returns the integral, given by the following:

$table with 1 row and 1 column , row1 column 1 , e r f . open x close , equals , fraction 2 , over square root of pi end root end fraction . integral , from , 0 , to , x , of . epsilon super negative z squared end super . d z , end table$

You can use the ERF function to find the probability (p) that a normally distributed random variable with mean 0 and standard deviation will take on a value less than X. For example, the quantity that is given by the following statement is equivalent to PROBNORM(X):

p=.5+.5*erf(x/sqrt(2));

Example

The following statements illustrate the ERF function:

Statement	Result
select erf(1.0);	0.8427007929
select erf(-1.0);	-0.842700793

ERF Function

Syntax

Arguments

expression

Details

Example

See Also