Linear interpolation in Microsft Excel: =IFERROR( IF( [@[x_axis]] = MAX(T_Inputs[x_axis]), INDEX(T_Inputs, MATCH([@[x_axis]], T_Inputs[x_axis], 1 ), MATCH([@[data_columns]], VALUE(T_Inputs[#Headers]), 0) ), ( INDEX(T_Inputs, MATCH([@[x_axis]], T_Inputs[x_axis],1), MATCH([@[data_columns]], VALUE(T_Inputs[#Headers]), 0 ) ) * ( IF([@[x_axis]] = MAX(T_Inputs[x_axis]), MAX(T_Inputs[x_axis]), INDEX(T_Inputs[x_axis], MATCH([@[x_axis]], T_Inputs[x_axis], 1 ) + 1) ) – [@[x_axis]] ) + IF([@[x_axis]] = MAX(T_Inputs[x_axis]), MAX(T_Inputs[x_axis]), […]