% mpicc -o jacobi jacobi.c -lm 
% mpirun -np 4 jacobi
At iteration 1, diff is 3.791438e+00
At iteration 2, diff is 1.948557e+00
At iteration 3, diff is 1.324536e+00
At iteration 4, diff is 1.014272e+00
At iteration 5, diff is 8.266808e-01
At iteration 6, diff is 6.992270e-01
At iteration 7, diff is 6.063208e-01
At iteration 8, diff is 5.354581e-01
At iteration 9, diff is 4.796424e-01
At iteration 10, diff is 4.345620e-01
At iteration 11, diff is 3.973794e-01
At iteration 12, diff is 3.661434e-01
At iteration 13, diff is 3.394715e-01
At iteration 14, diff is 3.163635e-01
At iteration 15, diff is 2.960832e-01
At iteration 16, diff is 2.780818e-01
At iteration 17, diff is 2.619444e-01
At iteration 18, diff is 2.473533e-01
At iteration 19, diff is 2.340625e-01
At iteration 20, diff is 2.218786e-01
At iteration 21, diff is 2.106480e-01
At iteration 22, diff is 2.002467e-01
At iteration 23, diff is 1.905738e-01
At iteration 24, diff is 1.815461e-01
At iteration 25, diff is 1.730939e-01
At iteration 26, diff is 1.651588e-01
At iteration 27, diff is 1.576911e-01
At iteration 28, diff is 1.506480e-01
At iteration 29, diff is 1.439927e-01
At iteration 30, diff is 1.376932e-01
At iteration 31, diff is 1.317215e-01
At iteration 32, diff is 1.260529e-01
At iteration 33, diff is 1.206656e-01
At iteration 34, diff is 1.155400e-01
At iteration 35, diff is 1.106589e-01
At iteration 36, diff is 1.060065e-01
At iteration 37, diff is 1.015689e-01
At iteration 38, diff is 9.733328e-02
At iteration 39, diff is 9.328799e-02
At iteration 40, diff is 8.942243e-02
At iteration 41, diff is 8.572687e-02
At iteration 42, diff is 8.219235e-02
At iteration 43, diff is 7.881060e-02
At iteration 44, diff is 7.557393e-02
At iteration 45, diff is 7.247523e-02
At iteration 46, diff is 6.950784e-02
At iteration 47, diff is 6.666555e-02
At iteration 48, diff is 6.394254e-02
At iteration 49, diff is 6.133332e-02
At iteration 50, diff is 5.883275e-02
At iteration 51, diff is 5.643598e-02
At iteration 52, diff is 5.413840e-02
At iteration 53, diff is 5.193567e-02
At iteration 54, diff is 4.982369e-02
At iteration 55, diff is 4.779852e-02
At iteration 56, diff is 4.585647e-02
At iteration 57, diff is 4.399400e-02
At iteration 58, diff is 4.220774e-02
At iteration 59, diff is 4.049448e-02
At iteration 60, diff is 3.885117e-02
At iteration 61, diff is 3.727490e-02
At iteration 62, diff is 3.576286e-02
At iteration 63, diff is 3.431241e-02
At iteration 64, diff is 3.292099e-02
At iteration 65, diff is 3.158617e-02
At iteration 66, diff is 3.030562e-02
At iteration 67, diff is 2.907711e-02
At iteration 68, diff is 2.789850e-02
At iteration 69, diff is 2.676776e-02
At iteration 70, diff is 2.568292e-02
At iteration 71, diff is 2.464211e-02
At iteration 72, diff is 2.364354e-02
At iteration 73, diff is 2.268547e-02
At iteration 74, diff is 2.176627e-02
At iteration 75, diff is 2.088434e-02
At iteration 76, diff is 2.003818e-02
At iteration 77, diff is 1.922632e-02
At iteration 78, diff is 1.844737e-02
At iteration 79, diff is 1.770000e-02
At iteration 80, diff is 1.698293e-02
At iteration 81, diff is 1.629491e-02
At iteration 82, diff is 1.563478e-02
At iteration 83, diff is 1.500140e-02
At iteration 84, diff is 1.439369e-02
At iteration 85, diff is 1.381060e-02
At iteration 86, diff is 1.325113e-02
At iteration 87, diff is 1.271434e-02
At iteration 88, diff is 1.219929e-02
At iteration 89, diff is 1.170511e-02
At iteration 90, diff is 1.123095e-02
At iteration 91, diff is 1.077600e-02
At iteration 92, diff is 1.033949e-02
At iteration 93, diff is 9.920652e-03