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              ESCi 118 – Numerical Methods to Engineering Problems
                                                QUIZ NO. 3
Due Date: Nov. 26, 2020
Instructions:
     Write a report that contains description of the problems, plan of solution, and
       interpretation of results. Explain clearly how each solution was obtained and show
       sample test runs whenever applicable.
     Submit a softcopy of this quiz by uploading it to our virtual classroom under Quiz
       No.3 (only when you cannot submit it through the virtual classroom that you need to
       email it to grace.curay@vsu.edu.ph).
PART I
Quiz No. 3 contains Part I, Part II, and III. In Part I, you are supposed to answer one (1)
problem only. Problem 1, Problem 2, and Problem 3 will be solved by a student with a last
digit number (0-3), (4-6), and (7-9) respectively of his/her Student ID.
Solve your assigned problem by using the three direct methods discussed in class namely:
Gauss Elimination, Gauss-Jordan, and LU Decomposition by Crout’s.
Problem 1:
               2 x1  x2  x3  2 x4  0
               x1  2 x2  x3  4 x4  3
               3 x1  x2  2 x3  x4  3
                x1  2 x2  x3  2 x4  13
Problem 2:
               2 x1  x2  x3  4 x4  19
                x1  2 x2  x3  2 x4  3
               2 x1  4 x2  2 x3  x4  25
                x1  x2  x3  2 x4  5
Problem 3:
               4 x1  3 x2  2 x3  x4  17
               2 x1  x2  2 x3  4 x4  11
               x1  2 x2  2 x3  x4  8
                2 x1  4 x2  5 x3  x4  15
PART II
The axial force Fi in each of the 13-member pin-connected truss, shown in the figure below,
can be calculated by solving the following system of 13 equations:
                   F2  0.707 F1  0,               F3  0.707 F1  2000  0
                   0.707 F1  F4  6229  0,        - F2  0.659 F5  F6  0
                    F4  0.753F5  600  0,         - F3  0.659 F5  F7  0
                   0.753F5  F8  0,                 - F6  0.659 F9  F10  0
                    F8  0.753F9  800  0,         - F7  0.659 F9  F11  0
                   0.753F9  F12  2429  0,         - F10  0.707 F13  0
                    F12  0.707 F13  600  0
Solve the system of equations using Gauss-Seidel iteration. Does the solution converge for a
starting (guess) vector whose elements are all zero?
PART III (15 points)
Find the solution of the equations:
f ( x, y )  x 2  xy  10  0
g ( x, y )  y  3xy 2  57  0
By taking the starting point as (1.5, 3.5) and TOL= 1x10 5 .
                                                                Prepared by:
                                                                Engr. Ma. Grace C. Sumaria