org.matheclipse.core.builtin.function

Class Count

java.lang.Object

org.matheclipse.core.eval.interfaces.AbstractCoreFunctionEvaluator

org.matheclipse.core.builtin.function.Count

All Implemented Interfaces:

ICoreFunctionEvaluator, IFunctionEvaluator, IEvaluator

public class Count
extends AbstractCoreFunctionEvaluator

Count the number of elements in an expression which match the given pattern.

Constructor Summary

Constructors

Constructor and Description
Count()

Method Summary

Modifier and Type	Method and Description
IExpr	evaluate(IAST ast, EvalEngine engine) Symbolic evaluation of a function.

Methods inherited from class org.matheclipse.core.eval.interfaces.AbstractCoreFunctionEvaluator

numericEval, setUp

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Count

public Count()

Method Detail

evaluate

public IExpr evaluate(IAST ast,
                      EvalEngine engine)

Description copied from class: AbstractCoreFunctionEvaluator

Symbolic evaluation of a function. ast.get(0) (or alternatively ast.head()) contains the head (i.e. the function symbol) of this abstract syntax tree (AST).
From ast.arg1() to ast.get(n) the ast contains the first to n-th argument of the function (alternatively you get the first to fifth argument with the methods arg1(), arg2(),... arg5()).
If necessary use the methods from the Validate class to check the number or types of arguments in the evaluate method.
Note: if the symbolic evaluation isn't possible or no result is found the evaluate method returns with a null value without throwing an exception!

Specified by:

evaluate in interface IFunctionEvaluator

Specified by:

evaluate in class AbstractCoreFunctionEvaluator

Parameters:

ast - the abstract syntax tree (AST) which should be evaluated

engine - the users current evaluation engine

Returns:

the evaluated object or null, if evaluation isn't possible

See Also:

Validate, IExpr.head(), IAST.arg1(), IAST.arg2(), IAST.arg3()