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vmultv

Performs mutiplication between two vectorial control signals

Syntax

vmultv  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)

vmultv multiplies two vectorial control signals, that is, each element of the first vector is processed (only) with the corresponding element of the other vector. 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 1 (i.e. the destination elements will not be changed). 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 1 (i.e. the destination vector will not be changed for these elements).

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

⚠ 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 multiplied). There is an i-rate version of this opcode called vmultv_i.

📝 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 vcella, adsynt, adsynt2 etc.

Examples

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

Example of the vmultv opcode.
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<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
vmultv 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 1 16 2

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     0.01    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>

See also

Operations Between two Vectorial Signals

Credits

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

New in Csound 5 (Previously available only on CsoundAV)