18.  Summation, Integral, Etc.

      Summations, integrals, and similar constructions are easy: sum from i=0 to {i= inf} x sup i
produces

Notice that we used braces to indicate where the upper part begins and ends. No braces were necessary for the lower part , because it contained no blanks. The braces will never hurt, and if the from and to parts contain any blanks, you must use braces around them.

      The from and to parts are both optional, but if both are used, they have to occur in that order.

      Other useful characters can replace the sum in our example: int prod union inter
become, respectively,

Since the thing before the from can be anything, even something in braces, from-to can often be used in unexpected ways: lim from {n -> inf} x sub n =0
is