pcalc: Perl based calculator
usage: pcalc [-D] [-3] 'EXPRESSION'
usage: pcalc [-D] [-3] SUMMAND_1 SUMMAND_2 ...
options: -D  use German decimal fraction symbol ,
examples:
  pcalc 2**8
  pcalc -3 2G+24M+16k
  pcalc -D 145,60 11,95 2,35
  
  Math operators: + - / * **
  Bool operators: || && !
  Functions:
    sqrt(x)     square root of x
    int(x)	integer of x
    rnd(x)	round of x
    sin(x)      sine of x, x is in radians
    cos(x)      cosine of x, x is in radians
    tan(x)      tangent of x, x is in radians
    atan(x)     arctangent of x, returns radians
    log(x)      natural logarithm of x
    exp(x)      exponential function of raising e to x
  Constants:
    pi = 3.14159265358979323844
    k  = 2**10 =             1,024
    M  = 2**20 =         1,048,576
    G  = 2**30 =     1,073,741,824
    T  = 2**40 = 1,099,511,627,776
  You may use [] instead of () to prevent shell evaluation