One 6x6 covariance block inside a parsed CCSDS OEM segment, held exactly as read.
lower_triangle holds the 21 lower-triangle values in keyword order CX_X,
CY_X, CY_Y ... CZ_DOT_Z_DOT, row by row. No definiteness check is
applied, so a matrix printed to a few digits that falls short of positive
semidefinite only through that rounding is read. cov_ref_frame is the
optional COV_REF_FRAME override, or nil to inherit the segment frame.
to_matrix/1 expands the values to six symmetric rows.
Summary
Functions
The symmetric 6x6 matrix, as six six-element rows, that the 21 lower-triangle values state. The values are placed as read; nothing is validated.