DownValues (Built-in Mathematica Symbol)

DownValues[f] gives a list of transformation rules corresponding to all downvalues defined for the symbol f.

Use Derivatives for Setting Up ... (Mathematica How To)

Mathematica 's functions for solving differential equations can be applied to many different classes of differential equations, including ordinary differential equations ...

Unevaluated (Built-in Mathematica Symbol)

Unevaluated[expr] represents the unevaluated form of expr when it appears as the argument to a function.

ReleaseHold (Built-in Mathematica Symbol)

ReleaseHold[expr] removes Hold, HoldForm, HoldPattern, and HoldComplete in expr.

HoldForm (Built-in Mathematica Symbol)

HoldForm[expr] prints as the expression expr, with expr maintained in an unevaluated form.

CompoundExpression (Built-in Mathematica Symbol)

expr_1; expr_2; ... evaluates the expr_i in turn, giving the last one as the result.

HoldAll (Built-in Mathematica Symbol)

HoldAll is an attribute which specifies that all arguments to a function are to be maintained in an unevaluated form.

MemoryConstrained (Built-in Mathematica Symbol)

MemoryConstrained[expr, b] evaluates expr, stopping if more than b bytes of memory are requested. MemoryConstrained[expr, b, failexpr] returns failexpr if the memory ...

TimeConstrained (Built-in Mathematica Symbol)

TimeConstrained[expr, t] evaluates expr, stopping after t seconds. TimeConstrained[expr, t, failexpr] returns failexpr if the time constraint is not met.

While (Built-in Mathematica Symbol)

While[test, body] evaluates test, then body, repetitively, until test first fails to give True.