public void GetSd() { // --- calculate sd List <double> lstMrLaw = new List <double>(); List <double> lstBlkLaw = new List <double>(); for (int i = 0; i < pivot.Count; i++) { int flag_mri = Convert.ToInt32(pivot[i].Flag_mri); CBatch_detail_aa_twofold current_row = pivot[i]; if (flag_mri == 1) { if (current_row.Law1 != null && current_row.ToString().Trim().Length != 0) { // -- blk double law_blk = Convert.ToDouble(current_row.Law1); lstBlkLaw.Add(law_blk); } if (current_row.Law2 != null && current_row.ToString().Trim().Length != 0) { // -- mr double law_mr = Convert.ToDouble(current_row.Law2); lstMrLaw.Add(law_mr); } } } Mri_measured = Convert.ToDouble(Standard_desviation(lstMrLaw)); Lrb_measured = Convert.ToDouble(Standard_desviation(lstBlkLaw)); }