Designed for usage in tsl_aggregate(). Uses linear regression to compute and return the slope of a numeric vector. Returns 0 if the length of the input vector is 1 or the linear regression fails.
See also
Other tsl_transformation:
f_binary(),
f_chi_squared(),
f_clr(),
f_detrend_difference(),
f_detrend_linear(),
f_hellinger(),
f_list(),
f_log(),
f_pca(),
f_percentage(),
f_proportion(),
f_proportion_sqrt(),
f_rescale_global(),
f_rescale_local(),
f_scale_global(),
f_scale_local(),
f_trend_linear()
