This is a good idea, standardising these calculations! That should remove a potential source of bugs.
Cheers, Edward On 28 July 2014 12:56, <[email protected]> wrote: > Author: tlinnet > Date: Mon Jul 28 12:56:51 2014 > New Revision: 24780 > > URL: http://svn.gna.org/viewcvs/relax?rev=24780&view=rev > Log: > Added function to calculate rotating frame paramters for lib/nmr.py. > > This function is called several times in specific_analyses/relax_disp/data.py > by plotting functions. > > sr #3124(https://gna.org/support/?3124): Grace graphs production for R1rho > analysis with R2_eff as function of Omega_eff. > sr #3138(https://gna.org/support/?3138): Interpolating theta through > spin-lock offset [Omega], rather than spin-lock field strength [w1]. > > Modified: > branches/r1rho_plotting/lib/nmr.py > > Modified: branches/r1rho_plotting/lib/nmr.py > URL: > http://svn.gna.org/viewcvs/relax/branches/r1rho_plotting/lib/nmr.py?rev=24780&r1=24779&r2=24780&view=diff > ============================================================================== > --- branches/r1rho_plotting/lib/nmr.py (original) > +++ branches/r1rho_plotting/lib/nmr.py Mon Jul 28 12:56:51 2014 > @@ -23,7 +23,7 @@ > """Module containing functions related to basic NMR concepts.""" > > # Python module imports. > -from math import pi > +from math import atan2, pi, sqrt > > # relax module imports. > from lib.physical_constants import g1H, return_gyromagnetic_ratio > @@ -95,3 +95,35 @@ > > # Convert and return. > return frq * 2.0 * pi * B0 / g1H * return_gyromagnetic_ratio(isotope) * > 1e-6 > + > + > +def rotating_frame_params(chemical_shift=None, spin_lock_offset=None, > omega1=None): > + """Calculate the rotating frame paramaters. > + > + @keyword chemical_shift: The chemical shift in rad/s. > + @type chemical_shift: float > + @keyword spin_lock_offset: spin-lock offset in rad/s. > + @type spin_lock_offset: float > + @keyword omega1: Spin-lock field strength in rad/s. > + @type omega1: float > + @return: The average resonance offset in the rotating > frame, angle describing the tilted rotating frame relative to the laboratory, > effective field in rotating frame. > + @rtype: float, float, float > + """ > + > + # The average resonance offset in the rotating frame. > + Delta_omega = chemical_shift - spin_lock_offset > + > + # Calculate the theta angle describing the tilted rotating frame > relative to the laboratory. > + # theta = atan(omega1 / Delta_omega). > + # If Delta_omega is negative, there follow the symmetry of atan, that > atan(-x) = - atan(x). > + # Then it should be: theta = pi + atan(-x) = pi - atan(x) = pi - > abs(atan( +/- x)). > + # This is taken care of with the atan2(y, x) function, which return > atan(y / x), in radians, and the result is between -pi and pi. > + if Delta_omega == 0.0: > + theta = pi / 2.0 > + else: > + theta = atan2(omega1, Delta_omega) > + > + # Calculate effective field in rotating frame. > + w_eff = sqrt( Delta_omega*Delta_omega + omega1*omega1 ) > + > + return Delta_omega, theta, w_eff > > > _______________________________________________ > relax (http://www.nmr-relax.com) > > This is the relax-commits 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-commits _______________________________________________ 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
