ndf
Location: lib, 9 Lines
; Scheme 9 from Empty Space, Function Library ; By Nils M Holm, 2015 ; Placed in the Public Domain ; ; (ndf real) ==> real ; (ndf* real) ==> real ; ; (load-from-library "ndf.scm") ; ; Compute the probability density at the given standard deviation ; (normal distribution function). Assuming a standard normal ; distribution. ; ; (Example:) (ndf 0) ==> 0.4 (define (ndf x) (* (/ (sqrt (* 2 pi))) (expt 2.71828182845904523536028747135266249775724709369995 (/ (- (* x x)) 2)))) (define (ndf* x mu sigma) (* (/ (* sigma (sqrt (* 2 pi)))) (expt 2.71828182845904523536028747135266249775724709369995 (- (/ (* (- x mu) (- x mu)) (* 2 (* sigma sigma)))))))