Fix divide-by-zero in domain_def_clm for degenerate 1x1 domains#65
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zhao7777 merged 1 commit intoHPSCTerrSys:tsmp-pdaf-patched-LAI_DAfrom Apr 1, 2026
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Bug: TSMP-PDAF crashes during CLM observation setup with a floating-point exception (divide by zero) in domain_def_clm (enkf_clm_mod_5.F90), e.g. when calling init_dim_obs_pdaf → domain_def_clm, see: #64
Cause: For a single land grid cell (1×1 domain), minlon == maxlon and minlat == maxlat after shifting by +180° / +90°, so (maxlon - minlon) and (maxlat - minlat) are zero. The code then maps observation lon/lat to grid indices by dividing by those spans. When observation coordinates differ slightly from the grid (e.g. float32 in NetCDF vs. double lonc/latc), the first branch can still be taken and divide by zero.
Fix: Compute longitudinal and latitudinal spans in real(r8) and treat the domain as degenerate when span ≤ 1.0e-6 (same units as lon+180 / lat+90).