Conversion to invert a rational constant of type :real.
DESCRIPTION
The call REAL_RAT_INV_CONV `inv c`, where c is a rational constant of type
:real, returns the theorem |- inv c = d where d is the canonical rational
constant that is equal to c's multiplicative inverse (reciprocal). The
constant c may be an integer constant (&n or -- &n), a ratio (&p / &q
or -- &p / &q), or a decimal (#DDD.DDDD or #DDD.DDDDeNN). The returned
value d is always put in the form &p / &q or -- &p / &q with q > 1 and
p and q sharing no common factor, or simply &p or -- &p when that is
impossible.
FAILURE CONDITIONS
Fails if applied to a term that is not the multiplicative inverse function
applied to one of the permitted forms of rational constant of type :real, or
if the constant is zero.