- [Function]
(rhythmrhythm [tempo] [beat])
Returns the value of rhythm converted to
seconds. Rhythm can be a proportion (number), a rhythmic
symbol or a list of the same. The optional tempo is a metronome
speed, and defaults to *tempo*. The optional
Beat parameter specifies the metronome's pulse and defaults
to *beat*.
A rhythmic symbol consists of a metric letter (Table 1) that may be
optionally preceded by a division letter: t for triplet
or q for quintuplet, and optionally followed by any
number of dots. Rhythmic symbols can be combined into simple
expressions involving addition, subtraction and multiplication.
Table 1. Table of metric letter.
| letter | value | letter | value | |
|---|---|---|---|---|
m | maxima | q | quarter | |
l | longa | e | eighth | |
b | brevis | s | sixteenth | |
w | whole | t | thirty-second | |
h | half | x | sixty-fourth |
Table 2 contains some examples of representative rhythmic tokens.
Table 2. Examples of rhythmic symbols and expressions.
| type | symbol |
|---|---|
| quarter | q |
| triplet quarter | tq |
| dotted-eight | e. |
| triplet dotted sixteenth | ts. |
| triple dotted half | h... |
| quintuplet whole | qw |
| sixteenth plus triplet quarter | s+tq |
| whole minus triplet sixteenth | w-ts |
| whole times 4 | w*4 |
Examples:
Example 1. Calculating rhythmic values.
(rhythm 'q) ⇒ 1.0 (rhythm 1/4 120.0) ⇒ .5 (rhythm 'w+q ) ⇒ 5.0 (define *tempo* 120.0) (rhythm '(q th e.. x) ) ⇒ (0.5 0.6666666666666666 0.4375 0.03125)