Hi Ed. You are correct.
I got confused yesterday, and thought the theta angle was between X, Z axis instead of the Z,X axis. Best Troels 2014-07-28 11:29 GMT+02:00 Edward d'Auvergne <[email protected]>: > Hi Troels, > > Do you have a literature reference where this is inverted? Have a > look at Art Palmer's 2001 review: > > - Palmer, A. G. III, Kroenke, C. D. and Loria J. P. (2001) Nuclear > Magnetic Resonance Methods for Quantifying Microsecond-to-Millisecond > Motions in Biological Macromolecules. Methods Enzymol., 339, 204-238. > (http://dx.doi.org/10.1016/S0076-6879(01)39315-1). > > Specifically at the top of page 216 where you can see: > > tan(theta) = omega1 / Omega. > > Therefore: > > theta = arctan(omega1 / Omega). > > So it should be correct in relax using the atan2() function. Or am I > missing something? > > Regards, > > Edward > > > > > > > On 25 July 2014 19:45, Troels Emtekær Linnet <[email protected]> wrote: >> Hi Edward. >> >> I was stumpling over the expression >> theta = atan2(omega1, Delta_omega) >> >> in: >> specific_analyses/relax_disp/data.py in return_offset_data(). >> >> atan2 requires: >> math.atan2(y, x) >> Return atan(y / x), in radians. The result is between -pi and pi. The >> vector in the plane from the origin to point (x, y) makes this angle >> with the positive X axis. The point of atan2() is that the signs of >> both inputs are known to it, so it can compute the correct quadrant >> for the angle. For example, atan(1) and atan2(1, 1) are both pi/4, but >> atan2(-1, -1) is -3*pi/4. >> >> But what is y, and x? >> >> If I look at my own figure at: >> http://wiki.nmr-relax.com/images/1/12/Fig1_Palmer_Massi_2006.png >> >> I would say that y is Delta_omega, and x is omega1. >> >> Have I done this wrong earlier? >> >> Best >> Troels >> >> _______________________________________________ >> relax (http://www.nmr-relax.com) >> >> This is the relax-devel mailing list >> [email protected] >> >> To unsubscribe from this list, get a password >> reminder, or change your subscription options, >> visit the list information page at >> https://mail.gna.org/listinfo/relax-devel _______________________________________________ relax (http://www.nmr-relax.com) This is the relax-devel mailing list [email protected] To unsubscribe from this list, get a password reminder, or change your subscription options, visit the list information page at https://mail.gna.org/listinfo/relax-devel
