Package com.singularsys.extensions.djep.diffRules

Class ChainRuleDiffRules

  • All Implemented Interfaces:
    DiffRulesI, JepComponent, java.io.Serializable
    Direct Known Subclasses:
    MacroDiffRules, MacroFunctionDiffRules
    public abstract class ChainRuleDiffRules
extends java.lang.Object
implements DiffRulesI
    Abstract base class for function which are differentiated using the chain rule. All subclasses should specify the name pfmc rules and descriptions fields. The rules specify the derivative of the function wrt i-th argument which is supplied as a Node Variable names in rules MUST be x,y for 1 to 2 variables. So for the function f(x,y) with two arguments if rules representing df/dx and df/dy are specified and x and y are functions of a further variable z then the derivative wrt z is found using the chain rule df(x,y)/dz -> df/dx * dx/dz + df/dy * dy/dz.
    See Also:
    Serialized Form

    • Constructor Detail

      • ChainRuleDiffRules

        protected ChainRuleDiffRules​(DJep djep)
        Constructor. Sub class should call a setup method to complete construction.

    • Method Detail

      • setup

        protected void setup​(java.lang.String funName,
                     PostfixMathCommandI pfmc,
                     Node rule,
                     java.lang.String description)
        Set the internal variables for unary function with argument named 'x'
        Parameters:
        funName - name of function
        pfmc - Jep function
        rule - expression for derivative wrt 'x'
        description - string rep of derivative

      • setup

        protected void setup​(java.lang.String funName,
                     PostfixMathCommandI pfmc,
                     Node rule1,
                     Node rule2,
                     java.lang.String description1,
                     java.lang.String description2)
        Set the internal variables for binary function with arguments named 'x' 'y'
        Parameters:
        funName - name of function
        pfmc - Jep function
        rule1 - expression for derivative wrt 'x'
        rule2 - expression for derivative wrt 'y'
        description1 - string rep of derivative
        description2 - string rep of derivative

      • setup

        protected void setup​(java.lang.String funName,
                     PostfixMathCommandI pfmc,
                     Node[] rules,
                     java.lang.String[] descriptions,
                     java.lang.String[] argNames)
        Set the internal variables for function with multiple arguments
        Parameters:
        funName - name of function
        pfmc - Jep function
        rules - expression for derivatives
        descriptions - text rep of derivatives
        argNames - names of the variables of the function

      • differentiate

        public Node differentiate​(ASTFunNode node,
                          java.lang.String var,
                          Node[] children,
                          Node[] dchildren)
                   throws JepException
        Use the chain rule to differentiate. diff(f(g(x),h(x)),x) -> df/dg * dg/dx + df/dh * dh/dx
        Specified by:
        differentiate in interface DiffRulesI
        var - The name of variable to differentiate wrt to.
        children - the arguments of the function
        dchildren - the derivatives of each argument of the function.
        Returns:
        top node of and expression tree for the derivative.
        Throws:
        JepException
        ParseException - if there is some problem in compiling the derivative.

      • init

        public void init​(Jep djep)
        Description copied from interface: JepComponent
        Initialize the component. This methods is called whenever a component is added to Jep. Hence it allows components to keep track of the other components they may rely on.
        Specified by:
        init in interface JepComponent
        Parameters:
        djep - the current Jep instance

      • getLightWeightInstance

        public JepComponent getLightWeightInstance()
        Description copied from interface: JepComponent
        Gets a light-weight instance suitable for using in multiple threads.
        Specified by:
        getLightWeightInstance in interface JepComponent
        Returns:
        either an new instance, null or 'this'.

      • getName

        public java.lang.String getName()
        returns the name of the function
        Specified by:
        getName in interface DiffRulesI

      • getPfmc

        public PostfixMathCommandI getPfmc()
        returns the PostfixMathCommandI for the function.

      • getNumRules

        public int getNumRules()
        Returns the number of rules which should be number of arguments of function

      • getRule

        public Node getRule​(int i)
        returns the i-th rule as an expression tree.

      • getDescriptions

        public java.lang.String[] getDescriptions()

      • getArgNames

        public java.lang.String[] getArgNames()

      • toString

        public java.lang.String toString()
        Description copied from interface: DiffRulesI
        Returns a string representation of the rule.
        Specified by:
        toString in interface DiffRulesI
        Overrides:
        toString in class java.lang.Object