class CAS::Ln
Representation for the `log(x)` function. It is implemented as a `CAS::Op`
Public Class Methods
# File lib/functions/fnc-trsc.rb, line 158 def self.init_simplify_dict @simplify_dict = { CAS::Zero => CAS.invert(CAS::Infinity), CAS::One => CAS::Zero, CAS::E => CAS::One } end
Public Instance Methods
Call resolves the operation tree in a `Numeric` (if `Fixnum`) or `Float` (depends upon promotions). As input, it requires an hash with `CAS::Variable` or `CAS::Variable#name` as keys, and a `Numeric` as a value
* **argument**: `Hash` with feed dictionary * **returns**: `Numeric`
# File lib/functions/fnc-trsc.rb, line 133 def call(f) # I'm leaving to Math the honor # of handling negative values... CAS::Help.assert(f, Hash) Math::log(@x.call(f)) end
Return the derivative of the `log(x)` function using the chain rule. The input is a `CAS::Op` because it can handle derivatives with respect to functions.
“`
d f'(x)
– log(f(x)) = ——- dx f(x) “`
* **argument**: `CAS::Op` object of the derivative * **returns**: `CAS::Op` a derivated object, or `CAS::Zero` for constants
# File lib/functions/fnc-trsc.rb, line 118 def diff(v) if @x.depend? v return CAS::One / @x else return CAS::Zero end end
Simplification callback. It simplify the subgraph of each node until all possible simplification are performed (thus the execution time is not deterministic).
* **returns**: `CAS::Op` simplified version
CAS::Op#simplify
# File lib/functions/fnc-trsc.rb, line 152 def simplify super return @x.x if @x.is_a? CAS::Exp return self.simplify_dictionary end
Convert expression to code (internal, for `CAS::Op#to_proc` method)
* **returns**: `String` that represent Ruby code to be parsed in `CAS::Op#to_proc`
# File lib/functions/fnc-trsc.rb, line 169 def to_code "Math::log(#{@x.to_code})" end
Returns the latex representation of the current Op
.
* **returns**: `String`
# File lib/functions/fnc-trsc.rb, line 176 def to_latex "\\log\\left( #{@x.to_latex} \\right)" end
Convert expression to string
* **returns**: `String` to print on screen
# File lib/functions/fnc-trsc.rb, line 143 def to_s "log(#{@x})" end