/// <summary>
        /// Returns the proportional modal damping data assigned to the specified load case.
        /// </summary>
        /// <exception cref="CSiException"><see cref="CSiApiBase.API_DEFAULT_ERROR_CODE" /></exception>
        public void FillDampingProportional()
        {
            if (_app == null)
            {
                return;
            }
            _app.GetDampingProportional(CaseName,
                                        out var dampingType,
                                        out var massProportionalDampingCoefficient,
                                        out var stiffnessProportionalDampingCoefficient,
                                        out var periodOrFrequencyPt1,
                                        out var periodOrFrequencyPt2,
                                        out var dampingPt1,
                                        out var dampingPt2);

            DampingProportional = new DampingProportional()
            {
                DampingType = dampingType,
                MassProportionalDampingCoefficient      = massProportionalDampingCoefficient,
                StiffnessProportionalDampingCoefficient = stiffnessProportionalDampingCoefficient,
                PeriodOrFrequencyPt1 = periodOrFrequencyPt1,
                PeriodOrFrequencyPt2 = periodOrFrequencyPt2,
                DampingPt1           = dampingPt1,
                DampingPt2           = dampingPt2
            };
        }
        // ====== Damping Proportional ======

        /// <summary>
        /// Returns the proportional modal damping data assigned to the specified load case.
        /// </summary>
        /// <exception cref="CSiException"><see cref="CSiApiBase.API_DEFAULT_ERROR_CODE" /></exception>
        protected void fillDampingProportional(IDampingProportional app)
        {
            if (app == null)
            {
                return;
            }
            app.GetDampingProportional(Name,
                                       out var dampingType,
                                       out var massProportionalDampingCoefficient,
                                       out var stiffnessProportionalDampingCoefficient,
                                       out var periodOrFrequencyPt1,
                                       out var periodOrFrequencyPt2,
                                       out var dampingPt1,
                                       out var dampingPt2);

            _dampingProportional = new DampingProportional()
            {
                DampingType = dampingType,
                MassProportionalDampingCoefficient      = massProportionalDampingCoefficient,
                StiffnessProportionalDampingCoefficient = stiffnessProportionalDampingCoefficient,
                PeriodOrFrequencyPt1 = periodOrFrequencyPt1,
                PeriodOrFrequencyPt2 = periodOrFrequencyPt2,
                DampingPt1           = dampingPt1,
                DampingPt2           = dampingPt2
            };
        }