README.md

cosmo

cosmo is a suite of add-on functions to the original Double Spike Toolbox. These functions allow for the optimization of a double spike suited for analyzing samples with mass-independent isotope effects (i.e., radiogenic excess, nucleosynthetic anomalies). These scripts can simply be copied and pasted to an existing download of the Double Spike Toolbox that has the 'fixed voltage' error model (v. 1.02 or later).

New functionalities

The seven additional (7) functions are described below:

1. calcratiocovIN.m
   Calculates the covariance matrix of the ratios that propagates the additional uncertainty from internal normalization. Ideally added to the 'private' folder of the original Double Spike Toolbox.

2. shake.m
   Sets up the parameters necessary for performing calculations with the errorwsplit.m and all dependent functions.

3. errorwsplit.m
   Similar to the original errorestimate.m function, but considers the splitting of the sample between spiked and unspiked measurements.

4. cosmo.m
   Similar to the original cocktail.m function, but considers the splitting of the sample between spiked and unspiked measurements.

5. errorcurve3.m
   Error curve that shows uncertainties in α as a function of the sample splitting (S) between spiked and unspiked measurements. The user also has the option to display the uncertainty in the standard/unspiked measurement in ε units.

6. errorcurve4.m
   Error curve that shows uncertainties in α as a function of the molar proportion of the spike (p) in the spike-sample mixture. Similar to the original errorcurve.m function uses an error model where the sample is split between a spiked and internally-normalized unspiked measurement.

7. errorsurface.m
   2d projection of error surface on α (or corresponding ppm/amu uncertainty) as a function of the sample splitting and the spike proportion in the spike-sample mixture.