Calculate slope of tangent on curve (Derivative)

[Toady]

;=======================================================
; Function: _SlopeOfTangent
; Author: Toady
;
; Action: Calculates the slope of of a tangent to a curve
;         Same as calculating the derivative in calculus
;
; $expr: String - Mathmatical expression
; $var: String - Independent variable
; $at_point: Number - x coordinate to evaluate slope
; $places: Integer - Places to round result (default = 4)
;
; Ex) y = x^2
;     dy/dx = 2x
;     dy/dx(2) = 4
; MsgBox(0,"Slope",_SlopeOfTangent("x^2","x",2))
;======================================================
Func _SlopeOfTangent($expr,$var,$at_point,$places=4)
    Local $dx = 0.00000001
    Local $x = $at_point
    Local $y = $x + $dx
    Local $slope = Execute(StringReplace($expr,$var,"$y")) - Execute(StringReplace($expr,$var,"$x"))
    Return Round($slope/$dx,$places)
EndFunc ;_SlopeOfTangent()==>

Here is a script I had to write for one of my courses in school. It is the same as calculating the derivative

of a function to determine the slope of a tangent point. Very simple!

[jvanegmond]

That is just too simple...

[WeMartiansAreFriendly]

That is just too simple...

would you have prefered it to be over 100 lines, or a full blown #include?