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Constants

The form of a numeric constant defined and illustrated in Part I is elaborated by the use of further letters, as in 2r3 for two-thirds, 2p1 for two π, and 2e3p1 for 2000 π. The complete scheme of numeric constants obeys the following hierarchy:
 . The decimal point is obeyed first _ The negative sign is obeyed next e Exponential (scientific) notation ad ar j Complex (magnitude and angle) in degrees or radians; Complex number p x Numbers based on pi (o.1) and on Euler’s number (the exponential ^1) b Base value (using a to z for 10 to 35)
Moreover, digits with a trailing x denote an extended precision integer, and digits followed by an r followed by further digits denote a rational number. See Section II G.

For example, 2.3 denotes two and three-tenths and _2.3 denotes its negation; but _2j3 denotes a complex number with real part _2 and imaginary part 3 , not the negation of the complex number 2j3 . Furthermore, symbols at the same level of the hierarchy cannot be used together: 1p2x3 is an ill-formed number.

The following lists illustrate the main points:
```   2.3e2 2.3e_2 2j3
230 0.023 2j3

2p1 1p_1
6.28319 0.31831

1x2 2x1 1x_1
7.38906 5.43656 0.367879