minor fixes

extra/math/derivatives/derivatives-docs.factor

@@ -17,20 +17,10 @@ HELP: derivative ( x function -- m )
     }
     { $notes
         "For applied scientists, you may play with the settings "
-        "in the source file to achieve arbitrary accuracy."
+        "in the source file to achieve arbitrary accuracy. "
     }
 } ;
 
-HELP: fast-derivative ( x function -- m )
-{ $values { "x" "a x-position on the function" } { "function" "a differentiable function" } }
-{ $description
-    "Approximates the slope of the tangent line of the provided function "
-    "by using a secant line with very near points. This implementation is "
-    "naive and is only provided because it is used in the much more "
-    "accurate " { $link derivative } " word. Use this word if accuracy "
-    "is of no importance."
-} ;
-
 HELP: derivative-func ( function -- der )
 { $values { "func" "a differentiable function" } { "der" "the derivative" } }
 { $description
@@ -48,6 +38,5 @@ HELP: derivative-func ( function -- der )
 ARTICLE: "derivatives" "The Derivative Toolkit"
 "A toolkit for computing the derivative of functions."
 { $subsection derivative }
-{ $subsection derivative-func }
-{ $subsection fast-derivative } ;
+{ $subsection derivative-func } ;
 ABOUT: "derivatives"

extra/math/derivatives/derivatives.factor

@@ -1,19 +1,13 @@
-! Copyright (c) 2008 Reginald Ford
 ! Tools for approximating derivatives
 
 USING: kernel math math.functions locals generalizations float-arrays sequences
 math.constants namespaces math.function-tools math.points math.ranges math.order ;
 IN: math.derivatives
 
-! Ridders' method of a derivative, from the chapter
-! "Accurate computation of F'(x) and F'(x)F''(x)",
-! From "Advances in Engineering Software, Vol. 4, pp. 75-76
-! \ fast-derivative has been factored out for use by children
-
 : largest-float ( -- x ) HEX: 7fefffffffffffff bits>double ; foldable
-: ntab 10 ;          ! max size of tableau (main accuracy setting)
-: con 1.41 ;       ! stepsize is decreased by this per-iteration
-: con2 1.9881 ;   ! con^2
+: ntab 10 ;         ! max size of tableau (main accuracy setting)
+: con 1.41 ;        ! stepsize is decreased by this per-iteration
+: con2 1.9881 ;     ! con^2
 : initial-h 0.02 ;  ! distance of the 2 points of the first secant line
 : safe 2.0 ;        ! return when current err is SAFE worse than the best
                     ! \ safe probably should not be changed
@@ -30,9 +24,6 @@ SYMBOL: matrix
         [ [ h get + ] dip eval ]
         [ [ h get - ] dip eval ]
     2bi slope ; inline
-: fast-derivative ( x function -- m )
-    over epsilon sqrt * h set
-    (derivative) ; inline
 : init-matrix ( -- )
         ntab [ ntab <float-array> ] replicate
     matrix set ;
@@ -70,5 +61,4 @@ SYMBOL: matrix
     ] all? drop
     ans get ; inline
 : derivative-func ( function -- function ) [ derivative ] curry ; inline
-: fast-derivative-func ( function -- function ) [ fast-derivative ] curry ; inline