
4.13.3 number operations
+
 addition

 negation or subtraction
*
 multiplication
/
 division
% , mod
 modulo
^ , **
 power, exponentiation (by an integer)
<=, >=, ==, <>
 comparison
mod
 integer modulo (the remainder of the division
div ), always nonnegative
Note: Quotient and exponentiation is only recognized as a
number expression if it is already a number, see Miscellaneous oddities.
For the behavior of comparison operators in rings with
ground field different from real or the rational numbers, see boolean expressions.
Example:
 ring r=0,x,dp;
number n = 1/2 +1/3;
n;
==> 5/6
n/2;
==> 5/12
1/2/3;
==> 1/6
1/2 * 1/3;
==> 1/6
n = 2;
n^2;
==> 1/4
// the following oddities appear here
2/(2+3);
==> // ** int division with `/`: use `div` instead in line >> 2/(2+3);<<
==> 0
number(2)/(2+3);
==> 2/5
2^2; // for int's exponent must be nonnegative
==> ? exponent must be nonnegative
==> ? error occurred in or before ./examples/number_operations.sing line 1\
2: ` 2^2; // for int's exponent must be nonnegative`
number(2)^2;
==> 1/4
3/4>=2/5;
==> 1
2/6==1/3;
==> 1

