When importing data into Simulink using From Workspace block the first column always represents time. So lets say we imported an array from workspace of dimension 1x100, it will take the 1st column as time and rest 99 columns as input. Therefore the answer of summation of all values will not be correct. To correct this while importing into Simulink add the first column value as 0 which signifies, provide input data to Simulink at t=0. If we put first column value as lets say 4, then the output of summation will be observed at t=4.