t p1 p2 p3 p4 ..... (unlimited)
This statement sets the tempo and specifies the accelerations and decelerations for the current section. This is done by converting beats into seconds.
p1 must be zero
p2 initial tempo in beats per minute
p3, p5, p7, ... times in beats (in non-decreasing order)
p4, p6, p8, ... tempi for the referenced beat times
Motion between different tempos over non-zero time is inverse linear. That is, an accelerando between two tempos M1 and M2 proceeds by linear interpolation of the single-beat durations from 60/M1 to 60/M2.
The first tempo given must be for beat 0.
A tempo, once assigned, will remain in effect from that time-point unless influenced by a succeeding tempo, i.e. the last specified tempo will be held to the end of the section.
A t statement applies only to the score section in which it appears. Only one t statement is meaningful in a section; it can be placed anywhere within that section. If a score section contains no t statement, then beats are interpreted as seconds (i.e. with an implicit t 0 60 statement).
N.B. If the csound command includes a -t flag, the interpreted tempo of all score t statements will be overridden by the command-line tempo.