Go to the first, previous, next, last section, table of contents.

## Referencing results and special numbers

An `@` used for an escape character; rules currently in force are as follows.

`@n`
  The evaluated result of n-th input command
`@@`
  The evaluated result of the last command
`@i`
  The unit of imaginary number, square root of -1.
`@pi`
  The number pi, the ratio of a circumference of the circle and its diameter.
`@e`
  Napier's number, the base of natural logarithm.
`@`
  A generator of GF(2^m), a finite field of characteristic 2, over GF(2). It is a root of an irreducible univariate polynomial over GF(2) which is set as the defining polynomial of GF(2^m).
`@>, @<, @>=, @<=, @==, @&&, @||`
  Fist order logical operators. They are used in quantifier elimination.

    [0] fctr(x^10-1);
    [[1,1],[x-1,1],[x+1,1],[x^4+x^3+x^2+x+1,1],[x^4-x^3+x^2-x+1,1]]
    [1] @@[3];
    [x^4+x^3+x^2+x+1,1]
    [2] eval(sin(@pi/2));
    1.000000000000000000000000000000000000000000000000000000000
    [3] eval(log(@e),20);
    0.99999999999999999999999999998
    [4] @0[4][0];
    x^4-x^3+x^2-x+1
    [5] (1+@i)^5;
    (-4-4*@i)
    [6] eval(exp(@pi*@i));
    -1.0000000000000000000000000000
    [7] (@+1)^9;
    (@^9+@^8+@+1)

As you can see in the above example, results of toplevel computation can be referred to by `@` convention. This is convenient for users, while it sometimes imposes a heavy burden to the garbage collector. It may happen that GC time will rapidly increase after computing a very large expression at the toplevel. In such cases `delete_history()` (see section `delete_history`) takes effect.

Go to the first, previous, next, last section, table of contents.