Extrapolate Pulsar Spins and Phase
[Common Pulsar APIs]

Collaboration diagram for Extrapolate Pulsar Spins and Phase:

Author:
Reinhard Prix Extrapolate the Pulsar spin-paramters $\{f^{(k)}\}\equiv\{f, \stackrel{.}{f},\ddot{f},...\}$, and "spin-ranges" $\{ f^{(k)}, \Delta f^{(k)} \}$ from one SSB epoch to another.
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Files

file  ExtrapolatePulsarSpins.h
 
Author:
Reinhard Prix Contains prototype for XLALExtrapolatePulsarSpins().

file  ExtrapolatePulsarSpins.c
 
Author:
Reinhard Prix Defines functions to extrapolate the pulsar spin-paramters $\{f, \stackrel{.}{f},\ddot{f},...\}$ from one SSB epoch to another.


Detailed Description

Author:
Reinhard Prix Extrapolate the Pulsar spin-paramters $\{f^{(k)}\}\equiv\{f, \stackrel{.}{f},\ddot{f},...\}$, and "spin-ranges" $\{ f^{(k)}, \Delta f^{(k)} \}$ from one SSB epoch to another.

Date:
Date
2008/04/08 09:42:33
The central function of this module is LALExtrapolatePulsarSpinRange(), which extrapolates a complete "spin range" (defined as LALPulsarSpinRange) from one epoch to another. A "spin-range" contains an epoch, and two vectors, $f^{(k)}$ and $\Delta f^{(k)}$ (where "canonical" ordering refers to $\Delta f^{(k)} >= 0$ for all k.

The extrapolation is defined by the pulsar spindown-model:

\[ f(\tau_1) = f(\tau_0) + {\stackrel{.}{f}(\tau_0) \over 1!} \,\Delta\tau + {\ddot{f}(\tau_0) \over 2!} \,\Delta\tau^2 + ... = \sum_{k=0}^s {f^{(k)}(\tau_0) \over k!}\, \Delta\tau^k\,, \]

where

\[\Delta\tau \equiv \tau_1 - \tau_0\f\,,\]

and therefore generally

\[ f^{(l)}(\tau_1) = \sum_{k=0}^{s - l} { f^{(k+l)}(\tau_0) \over k! }\, \Delta\tau^k\,. \]

This expression is used to extrapolate a whole "spin-range", namely at each spindown-order $(l)$ the extrapolated range is given by

\[ \min\left[ f^{(l)}(\tau_1) \right] = \sum_{k=0}^{s - l} {1\over k!} \min\left[ f^{(k+l)}(\tau_0) \, \Delta\tau^k \right]\,. \]

\[ \max\left[ f^{(l)}(\tau_1) \right] = \sum_{k=0}^{s - l} {1\over k!} \max\left[ f^{(k+l)}(\tau_0) \, \Delta\tau^k \right]\,. \]

This ensures that the range will be correctly extrapolated even if $\tau_1 < \tau_0$, i.e. $\Delta\tau < 0$.


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