% , True, False , EndOfFile , Infinity , Pi , Undefined .

# Constants

% | previous result
True, False | boolean constants
EndOfFile | end-of-file marker
Infinity | constant representing mathematical infinity
Pi | mathematical constant, pi
Undefined | constant signifying an undefined result

###

% -- previous result

##### Internal function

##### Calling format:

    %

##### Description:

`%` evaluates to the previous result on the command line. `%` is a global variable that is bound to the previous result from the command line. Using `%` will evaluate the previous result. (This uses the functionality offered by the `LazyGlobal` command).

Typical examples are `Simplify(%)` and `PrettyForm(%)` to simplify and show the result in a nice form respectively.

##### Examples:

    In> Taylor(x,0,5)Sin(x)
    Out> x-x^3/6+x^5/120;
    In> PrettyForm(%)

         3    5
        x    x
    x - -- + ---
        6    120

##### See also:

LazyGlobal .

###

True, False -- boolean constants

##### Internal function

##### Calling format:

    True
    False

##### Description:

`True` and `False` are typically a result of boolean expressions such as `2 < 3` or `True And False`.

##### See also:

And , Or , Not .

###

EndOfFile -- end-of-file marker

##### Internal function

##### Calling format:

    EndOfFile

##### Description:

End of file marker when reading from file. If a file contains the expression `EndOfFile;` the operation will stop reading the file at that point.

###

Infinity -- constant representing mathematical infinity

##### Standard library

##### Calling format:

    Infinity

##### Description:

Infinity represents infinitely large values. It can be the result of certain calculations.

Note that for most analytic functions Yacas understands `Infinity` as a positive number. Thus `Infinity*2` will return `Infinity`, and `a < Infinity` will evaluate to `True`.

##### Examples:

    In> 2*Infinity
    Out> Infinity;
    In> 2<Infinity
    Out> True;

###

Pi -- mathematical constant, pi

##### Standard library

##### Calling format:

    Pi

##### Description:

Pi symbolically represents the exact value of pi. When the `N()` function is used, `Pi` evaluates to a numerical value according to the current precision. This is performed by the function `Pi()` which always returns the numerical value. It is better to use `Pi` than `Pi()` except in numerical calculations, because exact simplification will be possible.

This is a "cached constant" which is recalculated only when precision is increased.

##### Examples:

    In> Sin(3*Pi/2)
    Out> -1;
    In> Sin(3*Pi()/2)
    Out> Sin(4.7123889804);
    In> Pi+1
    Out> Pi+1;
    In> N(Pi)
    Out> 3.14159265358979323846;

##### See also:

Sin , Cos , Precision , N , Pi() , CachedConstant .

###

Undefined -- constant signifying an undefined result

##### Standard library

##### Calling format:

    Undefined

##### Description:

`Undefined` is a token that can be returned by a function when it considers its input to be invalid or when no meaningful answer can be given. The result is then "undefined".

Most functions also return `Undefined` when evaluated on it.

##### Examples:

    In> 2*Infinity
    Out> Infinity;
    In> 0*Infinity
    Out> Undefined;
    In> Sin(Infinity);
    Out> Undefined;
    In> Undefined+2*Exp(Undefined);
    Out> Undefined;

##### See also:

Infinity .