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
