pub fn calc_ptdf(
case: &IndexedNetwork<'_>,
formula: BranchSusceptanceFormula,
) -> Result<CsMat<f64>>Expand description
PTDF (m × n): branch flows from nodal injections, f = PTDF · p. Every
reference bus column is zero. The DC bus susceptance matrix is grounded at
the whole reference set (reference_bus_indices), one row/column per slack.
One reference per island handles disconnected networks; several references
within one island fixes all of those bus angles to zero.