ptablei — Accesses table values by direct indexing with linear interpolation.


Accesses table values by direct indexing with linear interpolation.


ares ptablei andx, ifn [, ixmode] [, ixoff] [, iwrap]
ires ptablei indx, ifn [, ixmode] [, ixoff] [, iwrap]
kres ptablei kndx, ifn [, ixmode] [, ixoff] [, iwrap]


ifn -- function table number. The table need not be a power of 2 long.

ixmode (optional) -- index data mode. The default value is 0.

  • 0 = raw index

  • 1 = normalized (0 to 1)

ixoff (optional) -- amount by which index is to be offset. For a table with origin at center, use tablesize/2 (raw) or .5 (normalized). The default value is 0.

iwrap (optional) -- wraparound index flag. The default value is 0.

  • 0 = nowrap (index < 0 treated as index=0; index > tablesize sticks at index=size)

  • 1 = wraparound.


ptablei is a interpolating unit in which the fractional part of index is used to interpolate between adjacent table entries. The smoothness gained by interpolation is at some small cost in execution time (see also oscili, etc.), but the interpolating and non-interpolating units are otherwise interchangeable.


Here is an example of the ptablei opcode. It uses the file ptablei.csd.

Example 1363. Example of the ptablei opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

; Select audio/midi flags here according to platform
-odac     ;;;realtime audio out
;-iadc    ;;;uncomment -iadc if realtime audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o tablei.wav -W ;;; for file output any platform

sr = 44100
ksmps = 32
nchnls = 2
0dbfs  = 1

seed 0	;generate new values every time the instr is played

instr 1

ifn = p4
isize = p5
ithresh = 0.5
itemp ftgen ifn, 0, isize, 21, 2

iwrite_value = 0
i_index = 0
    iread_value ptablei i_index, ifn
    if iread_value > ithresh then
         iwrite_value = 1
         iwrite_value = -1
ptableiw iwrite_value, i_index, ifn
loop_lt i_index, 1, isize, loop_start


instr 2

ifn = p4
isize = ftlen(ifn)    
prints "Index\tValue\n"
i_index = 0
    ivalue tablei i_index, ifn
    prints "%d:\t%f\n", i_index, ivalue

  loop_lt i_index, 1, isize, loop_start		;read table 1 with our index

aout oscili .5, 100, ifn			;use table to play the polypulse
     outs   aout, aout

i 1 0 1 100 16
i 2 0 2 100

See Also

table, tablei, table3, ptable, ptable3, oscil1, oscil1i, osciln

More information on this opcode: , written by Jacob Joaquin


Author: John ffitch
Jan 2012

New in Csound version 5.16