6.7.5 Fraction Formats

Display of fractional numbers is controlled by the d o (calc-over-notation) command. By default, a number like eight thirds is displayed in the form ‘8:3’. The d o command prompts for a one- or two-character format. If you give one character, that character is used as the fraction separator. Common separators are ‘:’ and ‘/’. (During input of numbers, the : key must be used regardless of the display format; in particular, the / is used for RPN-style division, not for entering fractions.)

If you give two characters, fractions use “integer-plus-fractional-part” notation. For example, the format ‘+/’ would display eight thirds as ‘2+2/3’. If two colons are present in a number being entered, the number is interpreted in this form (so that the entries 2:2:3 and 8:3 are equivalent).

It is also possible to follow the one- or two-character format with a number. For example: ‘:10’ or ‘+/3’. In this case, Calc adjusts all fractions that are displayed to have the specified denominator, if possible. Otherwise it adjusts the denominator to be a multiple of the specified value. For example, in ‘:6’ mode the fraction ‘1:6’ will be unaffected, but ‘2:3’ will be displayed as ‘4:6’, ‘1:2’ will be displayed as ‘3:6’, and ‘1:8’ will be displayed as ‘3:24’. Integers are also affected by this mode: 3 is displayed as ‘18:6’. Note that the format ‘:1’ writes fractions the same as ‘:’, but it writes integers as ‘n:1’.

The fraction format does not affect the way fractions or integers are stored, only the way they appear on the screen. The fraction format never affects floats.