Replaced beta with rate for exponential distribution.

src/package.lisp

@@ -43,7 +43,7 @@
    #:left
    #:right
    #:r-exponential
-   #:beta
+   #:rate
    #:draw-standard-exponential
    #:r-normal
    #:mean

src/univariate.lisp

@@ -46,28 +46,28 @@ which has density exp(-x)."
 
 (declaim (inline draw-standard-exponential))
 
-(define-rv r-exponential (beta)
+(define-rv r-exponential (rate)
   (:documentation "Exponential(beta) distribution, with density
   beta*exp(-beta*x) on x >= 0.")
-  ((beta :type double-float :reader t))
-  (with-doubles (beta)
-    (assert (plusp beta))
-    (make :beta beta))
-  (mean () (/ beta))
-  (variance () (expt beta -2))
+  ((rate :type double-float :reader t))
+  (with-doubles (rate)
+    (assert (plusp rate))
+    (make :rate rate))
+  (mean () (/ rate))
+  (variance () (expt rate -2))
   (log-pdf (x &optional ignore-constant?)
            (declare (ignore ignore-constant?))
            (with-doubles (x)
-             (- (log beta) (* beta x))))
+             (- (log rate) (* rate x))))
   (cdf (x)
        (with-doubles (x)
-         (- 1 (exp (- (* beta x))))))
+         (- 1 (exp (- (* rate x))))))
   (quantile (p)
             (with-doubles (p)
               (check-probability p :right)
-              (/ (log (- 1 p)) (- beta))))
+              (/ (log (- 1 p)) (- rate))))
   (draw (&key)
-    (/ (draw-standard-exponential) beta)))
+        (/ (draw-standard-exponential) rate)))
 
 
 ;;; Normal distribution (univariate).