Commit 19567f9c401c519ea66f3a7820bab595b09290c6

Authored by Jürgen Knödlseder
1 parent 5499cfa5

Update user manual

doc/source/users/user_manual/likelihood.rst
@@ -179,7 +179,7 @@ Levenberg-Marquardt algorithm @@ -179,7 +179,7 @@ Levenberg-Marquardt algorithm
179 ctools uses an iterative Levenberg-Marquardt algorithm for maximum likelihood 179 ctools uses an iterative Levenberg-Marquardt algorithm for maximum likelihood
180 estimation. Since the Levenberg-Marquardt algorithm minimises a function, we 180 estimation. Since the Levenberg-Marquardt algorithm minimises a function, we
181 use :math:`-\ln L(M)` as the function to minimse. The Levenberg-Marquardt 181 use :math:`-\ln L(M)` as the function to minimse. The Levenberg-Marquardt
182 -algorithm starts with an inital guess of the :ref:`model <um_models>` parameters 182 +algorithm starts with an initial guess of the :ref:`model <um_models>` parameters
183 :math:`a_k` and iteratively replaces this estimate by a new estimate 183 :math:`a_k` and iteratively replaces this estimate by a new estimate
184 :math:`a_k + \Delta a_k`. The :math:`\Delta a_k` are determined by solving 184 :math:`a_k + \Delta a_k`. The :math:`\Delta a_k` are determined by solving
185 185
@@ -191,12 +191,12 @@ where @@ -191,12 +191,12 @@ where
191 .. math:: 191 .. math::
192 \alpha_{kl} = \frac{\partial^2 (-\ln L(M))}{\partial a_k \partial a_l} 192 \alpha_{kl} = \frac{\partial^2 (-\ln L(M))}{\partial a_k \partial a_l}
193 193
194 -is the curvature matrix 194 +is the curvature matrix,
195 195
196 .. math:: 196 .. math::
197 \beta_k = \frac{\partial (-\ln L(M))}{\partial a_k} 197 \beta_k = \frac{\partial (-\ln L(M))}{\partial a_k}
198 198
199 -is the gradient and 199 +is the gradient, and
200 :math:`\delta_{kl}` is the Kronecker delta that is :math:`1` for 200 :math:`\delta_{kl}` is the Kronecker delta that is :math:`1` for
201 :math:`k=l` and :math:`0` otherwise. :math:`\lambda` is a damping parameter 201 :math:`k=l` and :math:`0` otherwise. :math:`\lambda` is a damping parameter
202 that initially is set to 0.001. If a Levenberg-Marquardt iteration leads to 202 that initially is set to 0.001. If a Levenberg-Marquardt iteration leads to
@@ -247,8 +247,8 @@ where :math:`\ln L(M_s+M_b)` is the log-likelihood value obtained when @@ -247,8 +247,8 @@ where :math:`\ln L(M_s+M_b)` is the log-likelihood value obtained when
247 fitting the source and the background together to the data, and 247 fitting the source and the background together to the data, and
248 :math:`\ln L(M_b)` is the log-likelihood value obtained when fitting only 248 :math:`\ln L(M_b)` is the log-likelihood value obtained when fitting only
249 the background model to the data. 249 the background model to the data.
250 -Under the hypothesis that the model :math:`M_b` provides a satisfactory fit  
251 -of the data, :math:`TS` follows a :math:`\chi^2_n` distribution with 250 +Under the hypothesis that the model :math:`M_s+M_b` provides a satisfactory fit
  251 +of the data, :math:`\mathrm{TS}` follows a :math:`\chi^2_n` distribution with
252 :math:`n` degrees of freedom, where :math:`n` is the number of free parameters 252 :math:`n` degrees of freedom, where :math:`n` is the number of free parameters
253 in the source model component. Therefore 253 in the source model component. Therefore
254 254
@@ -256,9 +256,9 @@ in the source model component. Therefore @@ -256,9 +256,9 @@ in the source model component. Therefore
256 p = \int_\mathrm{TS}^{+\infty} \chi^2_n(x) \:\: \mathrm{d}x 256 p = \int_\mathrm{TS}^{+\infty} \chi^2_n(x) \:\: \mathrm{d}x
257 257
258 gives the chance probability (p-value) that the log-likelihood improves by 258 gives the chance probability (p-value) that the log-likelihood improves by
259 -:math:`TS/2` when adding the source model :math:`M_s` due to statistical 259 +:math:`\mathrm{TS}/2` when adding the source model :math:`M_s` due to statistical
260 fluctuations only. For :math:`n=1` the significance in Gaussian sigma 260 fluctuations only. For :math:`n=1` the significance in Gaussian sigma
261 -is given by :math:`\sqrt{TS}`. 261 +is given by :math:`\sqrt{\mathrm{TS}}`.
262 262
263 263
264 Upper flux limits 264 Upper flux limits