Function calculate_structural_pattern_jvp 

pub fn calculate_structural_pattern_jvp(
    cell: UnitCell,
    space_group: &SpaceGroup,
    input: &StructuralPatternInputView<'_>,
    tangent: &[f64],
) -> Result<StructuralPatternJvpResult, StructuralPatternError>

Calculate a full structural-pattern JVP without a dense pattern Jacobian.

Errors

Returns StructuralPatternError for invalid inputs or structural tangent.