Author: bugman
Date: Tue Jun 4 15:52:48 2013
New Revision: 19860
URL: http://svn.gna.org/viewcvs/relax?rev=19860&view=rev
Log:
Created the M61 2-site fast exchange dispersion model target function.
This is for the Meiboom 1961 model for 2-site fast exchange for R1rho-type
experiments. The code
for the func_M61() method was copied without modification from the
func_LM63() method.
Modified:
branches/relax_disp/target_functions/relax_disp.py
Modified: branches/relax_disp/target_functions/relax_disp.py
URL:
http://svn.gna.org/viewcvs/relax/branches/relax_disp/target_functions/relax_disp.py?rev=19860&r1=19859&r2=19860&view=diff
==============================================================================
--- branches/relax_disp/target_functions/relax_disp.py (original)
+++ branches/relax_disp/target_functions/relax_disp.py Tue Jun 4 15:52:48
2013
@@ -29,9 +29,10 @@
# relax module imports.
from lib.dispersion.cr72 import r2eff_CR72
from lib.dispersion.lm63 import r2eff_LM63
+from lib.dispersion.m61 import r2eff_M61
from lib.errors import RelaxError
from target_functions.chi2 import chi2
-from specific_analyses.relax_disp.variables import MODEL_CR72,
MODEL_LIST_FULL, MODEL_LM63, MODEL_NOREX, MODEL_R2EFF
+from specific_analyses.relax_disp.variables import MODEL_CR72,
MODEL_LIST_FULL, MODEL_LM63, MODEL_M61, MODEL_NOREX, MODEL_R2EFF
class Dispersion:
@@ -46,6 +47,7 @@
- 'No Rex': The model for no chemical exchange relaxation.
- 'LM63': The Luz and Meiboom (1963) 2-site fast exchange model.
- 'CR72': The Carver and Richards (1972) 2-site model for all
time scales.
+ - 'M61': The Meiboom (1961) 2-site fast exchange model for
R1rho-type experiments.
@keyword model: The relaxation dispersion model to fit.
@@ -112,6 +114,8 @@
self.func = self.func_LM63
if model == MODEL_CR72:
self.func = self.func_CR72
+ if model == MODEL_M61:
+ self.func = self.func_M61
def func_CR72(self, params):
@@ -206,6 +210,50 @@
return chi2_sum
+ def func_M61(self, params):
+ """Target function for the Meiboom (1961) fast 2-site exchange model
for R1rho-type experiments.
+
+ @param params: The vector of parameter values.
+ @type params: numpy rank-1 float array
+ @return: The chi-squared value.
+ @rtype: float
+ """
+
+ # Scaling.
+ if self.scaling_flag:
+ params = dot(params, self.scaling_matrix)
+
+ # Unpack the parameter values.
+ index = self.num_frq - 1
+ R20 = params[:index+1]
+ phi_ex = params[index+1]
+ kex = params[index+2]
+
+ # Initialise.
+ chi2_sum = 0.0
+
+ # Loop over the spins.
+ for spin_index in range(self.num_spins):
+ # Loop over the spectrometer frequencies.
+ for frq_index in range(self.num_frq):
+ # Convert phi_ex from ppm^2 to (rad/s)^2.
+ phi_ex_scaled = phi_ex * self.frqs[spin_index, frq_index]**2
+
+ # Back calculate the R2eff values.
+ r2eff_M61(r20=R20[frq_index], phi_ex=phi_ex_scaled, kex=kex,
cpmg_frqs=self.cpmg_frqs, back_calc=self.back_calc[spin_index, frq_index],
num_points=self.num_disp_points)
+
+ # For all missing data points, set the back-calculated value
to the measured values so that it has no effect on the chi-squared value.
+ for point_index in range(self.num_disp_points):
+ if self.missing[spin_index, frq_index, point_index]:
+ self.back_calc[spin_index, frq_index, point_index] =
self.values[spin_index, frq_index, point_index]
+
+ # Calculate and return the chi-squared value.
+ chi2_sum += chi2(self.values[spin_index, frq_index],
self.back_calc[spin_index, frq_index], self.errors[spin_index, frq_index])
+
+ # Return the total chi-squared value.
+ return chi2_sum
+
+
def func_NOREX(self, params):
"""Target function for no exchange.
r19860 - /branches/relax_disp/target_functions/relax_disp.py