unu 1op: Unary operation on a nrrd
Usage: unu 1op <operator> [-i <nin>] [-o <nout>]
<operator> = Unary operator. Possibilities include:
o "-": negative (multiply by -1.0)
o "r": reciprocal (1.0/value)
o "sin", "cos", "tan", "asin", "acos", "atan": same as in C
o "exp", "log", "log10": same as in C
o "sqrt", "ceil", "floor": same as in C
o "rup", "rdn": round up or down to integral value
o "abs": absolute value
o "sgn": -1, 0, 1 if value is <0, ==0, or >0
o "exists": 1 iff not NaN or +/-Inf, 0 otherwise
-i <nin> = input nrrd
-o <nout> = output nrrd (string); default: "-"
