vexpv

vexpv — Performs exponential operations between two vectorial control signals

Description

Performs exponential operations between two vectorial control signals

Syntax

vexpv  ifn1, ifn2, kelements [, kdstoffset] [, ksrcoffset] [,kverbose]

Initialization

ifn1 - number of the table hosting the first vector to be processed

ifn2 - number of the table hosting the second vector to be processed

Performance

kelements - number of elements of the two vectors

kdstoffset - index offset for the destination (ifn1) table (Default=0)

ksrcoffset - index offset for the source (ifn2) table (Default=0)

kverbose - Selects whether or not warnings are printed (Default=0)

vexpv elevates each element of ifn2 to the corresponding element of ifn1. Each vectorial signal is hosted by a table (ifn1 and ifn2). The number of elements contained in both vectors must be the same.

The result is a new vectorial control signal that overrides old values of ifn1. If you want to keep the old ifn1 vector, use vcopy_i opcode to copy it in another table. You can use kdstoffset and ksrcoffset to specify vectors in any location of the tables.

Negative values for kdstoffset and ksrcoffset are acceptable. If kdstoffset is negative, the out of range section of the vector will be discarded. If ksrcoffset is negative, the out of range elements will be assumed to be 0 (i.e. the destination elements will be set to 1). If elements for the destination vector are beyond the size of the table (including guard point), these elements are discarded (i.e. elements do not wrap around the tables). If elements for the source vector are beyond the table length, these elements are taken as 0 (i.e. the destination elements will be set to 1).

If the optional kverbose argument is different to 0, the opcode will print warning messages every k-pass if table lengths are exceeded.

[Warning] Warning

Using the same table as source and destination table in versions earlier than 5.04, might produce unexpected behavior, so use with care.

This opcode works at k-rate (this means that every k-pass the vectors are processed). There's an i-rate version of this opcode called vexpv_i.

[Note] Note

Please note that the elements argument has changed in version 5.03 from i-rate to k-rate. This will change the opcode's behavior in the unusual cases where the i-rate variable ielements is changed inside the instrument, for example in:

    instr 1
ielements  =        10
           vadd     1, 1, ielements
ielements  =        20
           vadd     2, 1, ielements
           turnoff
    endin

All these operators (vaddv, vsubv, vmultv, vdivv, vpowv, vexpv, vcopy and vmap) are designed to be used together with other opcodes that operate with vectorial signals such as bmscan, vcella, adsynt, adsynt2 etc.

Examples

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

Example 970. Example of the vexpv opcode.

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

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
; Audio out   Audio in
-odac           -iadc     ;;;RT audio I/O
; For Non-realtime ouput leave only the line below:
; -o cigoto.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr=44100
ksmps=128
nchnls=2

	instr 1
ifn1 = p4
ifn2 = p5
ielements = p6
idstoffset = p7
isrcoffset = p8
kval init 25
vexpv ifn1, ifn2, ielements, idstoffset, isrcoffset, 1
	endin

	instr 2	;Printtable
itable = p4
isize = ftlen(itable)
kcount init 0
kval table kcount, itable
printk2 kval

if (kcount == isize) then
  turnoff
endif

kcount = kcount + 1 
	endin


</CsInstruments>
<CsScore>

f 1 0 16 -7 1 16 17

f 2 0 16 -7 0 16 1

i2	0.0	0.2	1
i2	0.2	0.2	2
i1	0.4	0.01	1	2	5	3	8	
i2	0.8	0.2	1
i1	1.0	0.01	1	2	5	10	-2	
i2	1.2	0.2	1
i1	1.4	0.01	1	2	8	14	0	
i2	1.6	0.2	1
i1	1.8	0.002	1	2	8	0	14	
i2	2.0	0.2	1	
i1	2.2	0.002	1	1	8	5	2	
i2	2.4	0.2	1
e

</CsScore>
</CsoundSynthesizer>


Credits

Written by Gabriel Maldonado. Optional arguments added by Andres Cabrera and Istvan Varga.

New in Csound 5 (Previously available only on CsoundAV)