java - For Loop only printing/storing last iteration -

hope can make myself clear enough.

i'm trying measure how long take program multiply couple of matrices , storing result 1 (called c).

i need record time going 1 100, 1 200, 1 300, etc.

i'm measuring time , storing result .dat file ploting later on (using gnuplot)

thing is... when run it, last iteration n times wanted measure. let's i'm trying 1 100, 100 iterations, in .dat file, last iteration. i'm sorry if i'm not making myself clear.

here's code , can understand. thank you!!

import java.util.timer; import java.util.scanner;  public class matrixmult  {     public static void main(string[] args)      {         //creating new scanner input stdin//         scanner input =  new scanner(system.in);          //creates variable store nxn dimension of matrices//         int ms = input.nextint();          //initializing matrices , giving them dimensions provided stdin//         int [] [] = new int [ms] [ms];         int [] [] b = new int [ms] [ms];         int [] [] c = new int [ms] [ms];          //populating matrices 1's , 0's//         populatingmatrices (a);         populatingmatrices (b);          //closing scanner after being used//         input.close();          long t_start;         long t_end;         long t_cost = 00000000000l;          (int x = 0; x < ms ;x++ )          {             //starts timer//             t_start = system.nanotime();              //storing result of matrices multiplication c//             c = mmm(a,b,c);               //end timer             t_end = system.nanotime();              t_cost = t_end - t_start;              system.out.println();             system.out.println((t_cost / 1000000.0));         }      }//main method//      //method populate matrices 1's , 0's//     public static int [][] populatingmatrices(int [] [])     {         (int = 0; < a.length; i++)          {                (int j = 0; j < a[0].length; j++)              {                    if (i == j)                  {                     a[i][j] = 1;                 }                 else                  {                     a[i][j] = 0;                 }             }         //returns matrix populated 1's accross diagonal axis, , 0's in other elements of matrix//         }return a;     }         //method multiply identity matrices//     public static int [][] mmm (int [][], int b [][], int c [][])     {         int nr;         int nc;         nr = nc = a.length;          (int = 0; < nr; i++)          {             (int j = 0; j < nr ; j++ )              {                 (int k = 0;k < nr ;k++)                  {                     c[i][j] = c[i][j] + a[i][j] * b[k][j];                       }                }         }         return c;     } } 

thank much!

you getting last time of recent iteration because continuously overwriting value of t_cost. need += add each iteration of loop.

    long t_start;     long t_end;     long t_cost = 00000000000l;      (int x = 0; x < ms ;x++ )      {         //starts timer//         t_start = system.nanotime();          //storing result of matrices multiplication c//         c = mmm(a,b,c);           //end timer         t_end = system.nanotime();         //use += adding previous iterations of calcualted time         t_cost += t_end - t_start;          system.out.println();         system.out.println((t_cost / 1000000.0));     }