cov_double_time_trend
- pyoptex.doe.fixed_structure.cov.cov_double_time_trend(ntime_outer, ntime_inner, nruns)[source]
Covariance function to account for a double time trend. This is defined by a global time trend divided in ntime_outer sections, where each section has its own time trend consisting of ntime_inner sections.
Parameters
- ntime_outerint
The total number of global time sections.
- ntime_innerint
The total number of time sections per outer section, i.e., the number of nested sections.
- nrunsint
The total number of runs in the design.
Returns
- covfunc(Y, X)
The covariance function.