Functions available from code:

abs(value)
  = returns the absolute value of 'value'

sin(value)
  = returns the sine of the radian angle 'value'

cos(value)
  = returns the cosine of the radian angle 'value'

tan(value)
  = returns the tangent of the radian angle 'value'

asin(value)
  = returns the arcsine (in radians) of 'value'

acos(value)
  = returns the arccosine (in radians) of 'value'

atan(value)
  = returns the arctangent (in radians) of 'value'

atan2(value,value2)
  = returns the arctangent (in radians) of 'value'/'value2'

sqr(value)
  = returns the square of 'value'

sqrt(value)
  = returns the square root of 'value'

invsqrt(value)
  = returns the reciprocal of the  square root of 'value' (1/sqrt(value))
    (uses a fast approximation, may not always = 1/sqrt(value) :)

pow(value,value2)
  = returns 'value' to the power of 'value2'

exp(value)
  = returns e to the power of 'value'

log(value)
  = returns the log in base e of 'value'

log10(value)
  = returns the log in base 10 of 'value'

floor(value)
  = returns the largest integer less than or equal to 'value'

ceil(value)
  = returns the smallest integer greater than or equal to 'value'

sign(value)
  = returns the sign of 'value' (-1.0 or 1.0, or 0.0 or -0.0)

min(value,value2)
  = returns the smallest of 'value' and 'value2'

max(var,var2)
  = returns the greatest of 'value' and 'value2'

sigmoid(value,value2)
  = returns sigmoid function value of x='value' ('value2'=constraint)

rand(value)
  = returns a random integer between 0 and 'value'

band(value,value2)
  = returns a boolean AND of 'value' and 'value2'

bor(value,value2)
  = returns a boolean OR of 'value' and 'value2'

bnot(value)
  = returns a boolean NOT of 'value'

if(condition,valtrue,valfalse)
  = returns 'valtrue' if 'condition' is nonzero, returns 'valfalse' otherwise.
    new in AVS 2.8+: only one of valtrue/valfalse is evaluated, depending on condition

assign(dest, source)
  = if 'dest' is a variable, assigns the value of 'source' to it. returns the value of 'source'.
    a little trick: assign(if(v,a,b),1.0); is like if V is true, a=1.0, otherwise b=1.0. :)

exec2(parm1, parm2)
  = evaluates parm1, then parm2, and returns the value of parm2.

exec3(parm1, parm2, parm3)
  = evaluates parm1, then parm2, parm3, and returns the value of parm3.

equal(value,value2)
  = returns 1.0 if 'value' is equal to 'value2', otherwise returns 0.0

above(value,value2)
  = returns 1.0 if 'value' is greater than 'value2', otherwise returns 0.0

below(value,value2)
  = returns 1.0 if 'value' is less than 'value2', otherwise returns 0.0

megabuf(index)
  = can be used to get or set an item from the 1 million item temp buffer
    to get, use:   val=megabuf(index);
    to set, use:   assign(megabuf(index),val);

loop(count, statement)
  = executes <statement> <count> times. count is evaluated once and clamped
    to 0..4096. best used with exec2() and exec3() and assign(). Note that
    the return value of loop() is undefined and should not be used. 