Created
October 20, 2014 21:09
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ERROR_FUNCTION = ''' | |
CREATE OR REPLACE FUNCTION erf(x decimal) RETURNS decimal AS $$ | |
DECLARE a1 decimal = 0.254829592; | |
DECLARE a2 decimal = -0.284496736; | |
DECLARE a3 decimal = 1.421413741; | |
DECLARE a4 decimal = -1.453152027; | |
DECLARE a5 decimal = 1.061405429; | |
DECLARE p decimal = 0.3275911; | |
DECLARE sign integer = 1; | |
DECLARE t decimal; | |
DECLARE y decimal; | |
BEGIN | |
IF x < 0 THEN | |
sign := -1; | |
END IF; | |
x := @x; | |
t := 1.0/(1.0 + p*x); | |
y := 1.0 - (((((a5*t + a4)*t) + a3)*t + a2)*t + a1)*t*exp(-x*x); | |
RETURN sign*y; | |
END; $$ | |
LANGUAGE PLPGSQL; |
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