Wolfram: Force Numerical Result
(in Java and other languages, similar idea is “casting”.)
Symbolic Result vs Numerical Result
All computation are done symbolically by default, returning symbolic (exact) result.
For example, 3/2 return just itself (does not become 1.5).
And 6/4
return the rational number 3/2.
Another example:
1/2 + 1/3
return 5/6
3/2 (* return itself *) 1/2 + 1/3 (* 5/6 *)
If parts of expression contains approximate number, then the result is approximate.
3/2 + 5/9. (* return 2.05556 *)
Convert Exact Number to Approximate (Machine Number)
use
N[expression]
to convert numbers in expression to machine precision numbers.
N[3/2] (* return 1.5 *)
A common way to use N is via postfix notation,
That is,
N[expr]
is the same as
expr//N
x = ((1/2)^5 + (3/2)^2)^3 (* 389017/32768 *) x //N (* 11.871856689453125 *)