PLEASE NOTE: THIS IS AN OLD VERSION. The current version is linked from The Complete Lojban Language.

4. Special numbers

The following cmavo are discussed in this section:

   ci'i    PA  infinity
    ka'o    PA  imaginary i, sqrt(-1)
    pai PA  pi (approx 3.14159...)
    te'o    PA  exponential e (approx 2.71828...)
    fi'u    PA  golden ratio, phi,
            (1 + sqrt(5))/2 (approx. 1.61803...)
The last cmavo is the same as the fraction sign cmavo: a fraction sign with neither numerator nor denominator represents the golden ratio.

Numbers can have any of these digit, punctuation, and special-number cmavo of Sections 2, 3, and 4 in any combination:

4.1)  ma'u ci'i
    +¥
4.2)  ci ka'o re
    3i2 (a complex number equivalent to ``3 + 2i'')
Note that ``ka'o'' is both a special number (meaning ``i'') and a number punctuation mark (separating the real and the imaginary parts of a complex number).

4.3)  ci'i no
    infinity zero
    À
0 (a transfinite cardinal)

The special numbers ``pai'' and ``te'o'' are mathematically important, which is why they are given their own cmavo:

4.4)  pai
    pi

4.5)   te'o
    e
However, many combinations are as yet undefined:
4.6)  pa pi re pi ci
    1.2.3

4.7)   pa ni'u re
    1 negative-sign 2
Example 4.5 is not ``1 minus 2'', which is represented by a different cmavo sequence altogether. It is a single number which has not been assigned a meaning. There are many such numbers which have no well-defined meaning; they may be used for experimental purposes or for future expansion of the Lojban number system.

It is possible, of course, that some of these ``oddities'' do have a meaningful use in some restricted area of mathematics. A mathematician appropriating these structures for specialized use needs to consider whether some other branch of mathematics would use the structure differently.

More information on numbers may be found in Sections 8 to 12.