On Mar 28, 10:47 pm, "aeneng" <[EMAIL PROTECTED]> wrote: > Hello everyone,
Hi, Always avoid reinventing the wheel: from Numeric import array, cross_product a = array([1, 2, 3]) b = array([4, 5, 6]) print cross_product(a, b) See: http://numpy.scipy.org/ http://www.scipy.org/ (hint: consider that many people want to multiply matrices) :-) > > I am just starting to use python in numerical cacluation. > I need you to help me to see what's wrong with the following piece of > codes, which computes the cross product of two vectors and returns > the result. u and v are two 3x1 matrix. > > when I import the function, error message show like this>>> import cross > > Traceback (most recent call last): > File "<stdin>", line 1, in ? > File "cross.py", line 8 > ppp2=u[2]*v[0]-u[0]*v[2] > ^ > SyntaxError: invalid syntax > > WHAT IS WRONG WITH MY CODE? > > I appreciate your help. > > ##here is the function definition. > ##cross.py## > def cross(u,v) > """input two vectors u and v in 3-D space, > output a cross product of vector w, in column or in row > accordingly.""" > ppp1,ppp2,ppp3=0.0,0.0,0.0 > ppp1=u[1]*v[2]-u[2]*v[1] > ppp2=u[2]*v[0]-u[0]*v[2] > ppp3=u[0]*v[1]-u[1]*v[0] > # store the result of the cross product in u > u[0]=ppp1 > u[1]=ppp2 > u[2]=ppp3 > return u #return the cross product of vector u x v. > if __name__=="__main__": > from cvxopt.base import matrix > u=matrix([1.0,0.0,0.0],(3,1)) > v=matrix([0.0,1.0,0.0],(3,1)) > print cross(u,v) > print "file name is %s" %__name__ -- http://mail.python.org/mailman/listinfo/python-list
