4.11.2 number expressions
-------------------------

A number expression is:
1. a rational number (there are NO spaces allowed inside a rational number,
see int expressions)
2. a floating point number (if the coefficient field is real):

<digits>.<digits>e<sign><digits>
3. an identifier of type number
4. a function returning number
5. an int expression (see Type conversion and casting)
6. number expressions combined by the arithmetic operations
+, -, *, /, ^, or **.
7. a type cast to number


Example:
  // the following expressions are in any ring int expressions
  2 / 3;
==> 0
  4/ 8;
==> 0
  2 /2;   // the notation of / for div might change in the future
==> 1
  ring r0=0,x,dp;
  2/3, 4/8, 2/2 ; // are numbers
==> 2/3 1/2 1

  poly f = 2x2 +1;
  leadcoef(f);
==> 2
  typeof(_);
==> number
  ring rr =real,x,dp;
  1.7e-2; 1.7e+2; // are valid (but  1.7e2 not), if the field is `real`
==> 1.700e-02
==> 1.700e+02
  ring rp = (31,t),x,dp;
  2/3, 4/8, 2/2 ; // are numbers
==> 11 -15 1
  poly g = (3t2 +1)*x2 +1;
  leadcoef(g);
==> (3t2+1)
  typeof(_);
==> number
  par(1);
==> (t)
  typeof(_);
==> number
See
Type conversion and casting;
ring.

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&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; User manual for <a href="http://www.singular.uni-kl.de/"><i>Singular</i></a> version 2-0-4, October 2002,
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