question: public Vector ( final Vector A , final double BX , final double BY , final double BZ ) { final double thisX = A . y * BZ - A . z * BY ; final double thisY = A . z * BX - A . x * BZ ; final double thisZ = A . x * BY - A . y * BX ; final double magnitude = magnitude ( thisX , thisY , thisZ ) ; if ( Math . abs ( magnitude ) < MINIMUM_RESOLUTION ) { throw new IllegalArgumentException ( "Degenerate/parallel vector constructed" ) ; } final double inverseMagnitude = 1.0 / magnitude ; this . x = thisX * inverseMagnitude ; this . y = thisY * inverseMagnitude ; this . z = thisZ * inverseMagnitude ; }
target:  Construct a vector that is perpendicular to two other (non-zero) vectors.  If the vectors are parallel, IllegalArgumentException will be thrown. Produces a normalized final vector.