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\(-\)

Subtraction operator.

Arithmetic operators perform operations of change-sign (negate), don't-change-sign, logical AND logical OR, add, subtract, multiply and divide. Note that a value or an expression may fall between two of these operators, either of which could take it as its left or right argument, as in

\[ a + b * c. \]

In such cases three rules apply:

  1. \(*\) and \(/\) bind to their neighbors more strongly than \(+\) and \(-\). Thus the above expression is taken as:
    \(a + (b * c)\) with \(*\) taking \(b\) and \(c\) and then \(+\) taking \(a\) and \(b * c\).

  2. \(+\) and \(-\) bind more strongly than &&, which in turn is stronger than ||:
    \(a \;\&\&\; b - c \;||\; d\) is taken as \((a \;\&\&\; (b - c))\;||\; d\)

  3. When both operators bind equally strongly, the operations are done left to right:
    \(a - b - c\) is taken as \((a - b) - c\)

Parentheses may be used as above to force particular groupings.

Syntax

-a  (no rate restriction)
a - b  (no rate restriction)

where the arguments \(a\) and \(b\) may be further expressions.

Arguments

The arguments of \(-\) can be scalar values or k-rate one dimensional arrays (vectors), or any combination. If one of the arguments is an array, so is the value.

Examples

Here is an example of the - operator. It uses the file subtracts.csd.

Example of the - operator.
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<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
; Audio out   Audio in    No messages
-odac    ;;;realtime audio I/O
; For Non-realtime ouput leave only the line below:
; -o -.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

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

instr 1

idur = p3
iatt = p4
idec = p5
isus = p3-iatt-idec                             ;calculate sustain time from subtracting attack and decay
printf_i "sutain time= note duration - attack - decay --> %.1f-%.1f-%.1f = %.1f\n", 1, idur, iatt, idec, isus

kenv expseg 0.01, iatt, 1, isus, 1, idec, 0.01  ;envelope
asig poscil 1*kenv, 200, 1
     outs asig, asig

endin
</CsInstruments>
<CsScore>
f 1 0 4096 10 1 ;sine wave
;      attack decay
i 1 0 3 .1     .2
i 1 4 3 .5    1.5
i 1 8 5  4     .5

e
</CsScore>
</CsoundSynthesizer>

Its output should include lines like these:

sutain time= note duration - attack - decay --> 3.0-0.1-0.2 = 2.7
sutain time= note duration - attack - decay --> 3.0-0.5-1.5 = 1.0
sutain time= note duration - attack - decay --> 5.0-4.0-0.5 = 0.5

See also

Arithmetic and Logic Operations

Credits

Arithmetic on vectors is new in version 6.00