# [Numpy-discussion] Faster way to generate a rotation matrix?

Jonathan Taylor jonathan.taylor@utoronto...
Tue Mar 3 17:53:44 CST 2009

```Sorry.. obviously having some copy and paste trouble here.  The
message should be as follows:

Hi,

I am doing optimization on a vector of rotation angles tx,ty and tz
using scipy.optimize.fmin.  Unfortunately the function that I am
optimizing needs the rotation matrix corresponding to this vector so
it is getting constructed once for each iteration with new values.
>From profiling I can see that the function I am using to construct
this rotation matrix is a bottleneck.  I am currently using:

def rotation(theta):
tx,ty,tz = theta

Rx = np.array([[1,0,0], [0, cos(tx), -sin(tx)], [0, sin(tx), cos(tx)]])
Ry = np.array([[cos(ty), 0, -sin(ty)], [0, 1, 0], [sin(ty), 0, cos(ty)]])
Rz = np.array([[cos(tz), -sin(tz), 0], [sin(tz), cos(tz), 0], [0,0,1]])

return np.dot(Rx, np.dot(Ry, Rz))

Is there a faster way to do this?  Perhaps I can do this faster with a
small cython module, but this might be overkill?

Thanks for any help,
Jonathan.
```