Difference between revisions of "Programmer Guide/Command Reference/NUM"

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The ''expression'' will be evaluated numerically, and the result (textual representation) will be returned. The ''expression'' may consist of the following parts:
 
The ''expression'' will be evaluated numerically, and the result (textual representation) will be returned. The ''expression'' may consist of the following parts:
;decimal numbers: <code>123.456, 17.5e3, 100, -312.123, 1e-3</code>
+
;decimal numbers: <code>123.456</code>, <code>17.5e3</code>, <code>100</code>, <code>-312.123</code>, <code>1e-3</code>,&hellip;
;hexa-decimal numbers:<code>0x1234, 0xabc, 0XabC</code>
+
;hexa-decimal numbers:<code>0x1234</code>, <code>0xabc</code>, <code>0XabC</code>, &hellip;
 
;special constants:<code>pi</code> (=3.1415...), <code>e</code> (=2.71828...),  
 
;special constants:<code>pi</code> (=3.1415...), <code>e</code> (=2.71828...),  
 
:<code>rand</code> (a linear distributed pseudo random number ''r''; -1&le;''r''&lt;1)
 
:<code>rand</code> (a linear distributed pseudo random number ''r''; -1&le;''r''&lt;1)
 
:<code>lran</code> (a linear distributed pseudo random number ''r''; 0&le;''r''&lt;1)
 
:<code>lran</code> (a linear distributed pseudo random number ''r''; 0&le;''r''&lt;1)
;numerical operators:<code>-''a''</code> (negate), <code>''a''+''b''</code> (add), <code>''a''-''b''</code> (subtract), <code>''a''*''b''</code> (multiply), <code>''a''/''b''</code> (divide), <code>''a''%''b''</code> (modulo), <code>''a''^''b'' (power)</code>
+
;numerical operators: <code>-''a''</code> (negate), <code>''a''+''b''</code> (add), <code>''a''-''b''</code> (subtract), <code>''a''*''b''</code> (multiply), <code>''a''/''b''</code> (divide), <code>''a''%''b''</code> (modulo), <code>''a''^''b'' (power)</code>
 
;logical operators (bitwise): <code>!''a</code> (not), <code>''a''&''b''</code> (and), <code>''a''|''b''</code> (or), <code>''a''^''b''</code> (exclusive or)
 
;logical operators (bitwise): <code>!''a</code> (not), <code>''a''&''b''</code> (and), <code>''a''|''b''</code> (or), <code>''a''^''b''</code> (exclusive or)
 
;brackets:<code>(''expression'')</code>
 
;brackets:<code>(''expression'')</code>

Revision as of 17:48, 25 April 2014

command return value value of RC
NUM expression value of expression or
empty string if the evaluation fails
0
error code
NUMCHECK expression value of expression or
empty string if the evaluation fails
0
warning code

The expression will be evaluated numerically, and the result (textual representation) will be returned. The expression may consist of the following parts:

decimal numbers
123.456, 17.5e3, 100, -312.123, 1e-3,…
hexa-decimal numbers
0x1234, 0xabc, 0XabC, …
special constants
pi (=3.1415...), e (=2.71828...),
rand (a linear distributed pseudo random number r; -1≤r<1)
lran (a linear distributed pseudo random number r; 0≤r<1)
numerical operators
-a (negate), a+b (add), a-b (subtract), a*b (multiply), a/b (divide), a%b (modulo), a^b (power)
logical operators (bitwise)
!a (not), a&b (and), a|b (or), a^b (exclusive or)
brackets
(expression)
functions
setlran(seed) linear distributed pseudo random number r (0≤r<1)
seed is the start value (0≤seed&lt<1)
sin(x), cos(x), tan(x) sine, cosine or tangent of x
asin(x), acos(x), atan(x) inverse sine, cosine or tangent of x
exp(x) computes ex
log(x) common logarithm of x (base 10)
ln(x) natural logarithm of x (base e)
sqrt(x) square root of x (base 10)
abs(x) absolute value of x (base 10)
int(x) integer part of x, the fractional part is truncated
(range of x: 32bit signed integer)
round(x) round to the nearest integer of x
(range of x: 32bit signed integer)
db(x) convert level to factor (10x/20)
sinc(x), sinx(x) sinc function: sin(x) / x
sign(x) sign of x; returns -1 if x<0, otherwise 1
hz2bark(x) convert x from Hertz to Bark
bark2hz(x) convert x from Bark to Hertz
bit(n) returns the integer with only bit n (0≤n<32) is set and all other are cleared; can be used to generate bit masks
floor(x) returns a floating-point value representing the largest integer that is less than or equal to x
(range of x: 64bit float)
iserr(rc), iserror(rc) returns 1 if rc is a STx error code, otherwise 0
this function can be used to test the completion code RC of a command
iswarn(rc), iswarning(rc) returns 1 if rc is a STx warning code, otherwise 0
this function can be used to test the completion code RC of a command
npow2(n) next power of 2; returns the smallest possible value 2mn
Notes
  • In case of the expression being syntactically ill-formed, an error (NUM) or warning (NUMCHECK) is reported.
  • The special numerical objects (vectors, matrices) available in EVAL-expressions, can not be used in the NUM expressions. Only the use of numerical constants and variables is possible.
  • The same expression syntax is used for the INT and INTCHECK, for the numerical expressions in conditions (e.g. IF or WHILE) and for the evaluation of numerical arguments of commands.
  • Numerical expressions are evaluated in 64bit floating point precission.
  • For logical (operators !, &, |, ^) and integer expressions (functions round, int, bit) 32bit signed integers are used.
See also
INT, INTCHECK, EVAL, EVALCHECK, SEGMENT
Examples
// #wave = wave item
#t := num $#wave[!length] / $#wave[!srate]          // duration in seconds
// #t = frame length in seconds, #o = overlap in percent
#lfrm := int $#t * $#wave[!srate]                   // frame length in samples
#lhop := int $#t * (1 - $#o / 100) * $#wave[!srate] // hopsize in samples
#lfft := int npow2($#lfrm)                          // fft length
#df   := num $#wave[!srate] / $#lfft                // frequency resolution
// using expressions in a IF statement
if 'db($#level)' > 1 then
    conlog 'level must be lower or equal 0dB'
    #level := 0
end