Diagnostics for stored single-target TMM solutions

Reuses the stored transition-matrix blocks to compute a compact set of numerical and physics-based diagnostics for one or more stored frequencies. The summary combines:

• monostatic reconstruction residuals,

• reciprocity residuals under incident/receive-angle exchange,

• an optical-theorem residual based on forward scattering and the integrated differential cross section,

• block-level conditioning indicators from the stored transition-matrix blocks,

• and, for prolate/oblate targets, an equal-volume sphere-to-spheroid continuation path that checks whether the monostatic response deforms smoothly away from the exact sphere limit.

These checks are meant to help distinguish "the post-processing is self-consistent" from "the retained solve was also numerically comfortable," which is especially helpful for the newer nonspherical TMM branches. For stored cylinders, the current diagnostics are intentionally limited to exact monostatic reconstruction because a validated retained cylinder angular operator is not yet available.

Usage

tmm_diagnostics(
  object,
  frequency = NULL,
  theta_body = NULL,
  phi_body = NULL,
  reciprocity_pairs = NULL,
  n_theta = 61,
  n_phi = 121,
  continuation_steps = 6L
)

Arguments

object

Scatterer-object previously evaluated with target_strength(..., model = "TMM", store_t_matrix = TRUE).

frequency

Optional stored frequency or vector of stored frequencies (Hz). Defaults to all stored frequencies.

theta_body

Incident polar angle (radians) used for the monostatic and optical-theorem checks. Defaults to the stored TMM incident angle.

phi_body

Incident azimuth angle (radians) used for the monostatic and optical-theorem checks. Defaults to the stored TMM incident angle.

reciprocity_pairs

Optional data frame giving explicit reciprocity test angles. Must contain theta_body, phi_body, theta_scatter, and phi_scatter columns in radians.

n_theta

Number of polar-angle grid points used by the optical-theorem integration check.

n_phi

Number of azimuth-angle grid points used by the optical-theorem integration check.

continuation_steps

Number of equal-volume aspect-ratio steps used for the sphere-to-spheroid continuation check on prolate and oblate targets. Set to 0 or 1 to skip the continuation path. Ignored for non-spheroidal targets.

Value

A list with components:

summary

Per-frequency diagnostic summary.

block_metrics

Per-frequency block-level conditioning and transpose-residual summaries.

continuation

Equal-volume sphere-to-spheroid continuation path for spheroidal targets, or NULL for other shapes.

See also

tmm_scattering, tmm_scattering_grid, tmm_products