CS314 Summer 2003

Midterm Exam

Name:_____________________________________

Problem
Max.
Grade
1.
10

2.
10

3.
10

4.
15

5.
15

6.
10

7.
10

8.
10

9.
10

Total:
100




























1. (10 pts) Write the decimal representation for the following floating point number in binary

11000000 00110011 00000000 00000000 00000000 00000000 00000000 00000000








































2. (10 pts) If the bisection method is used to find the solution for f(x) =0 starting at the interval [a,b], how many iterations are necessary so that the error /xk-xk-1/ < epsilon? Consider the interval [a,b] as the first iteration.












































3. (10 pts.) Use the false position method to compute c0, c1, c2, c3 using the function ex - 2 - x = 0 starting at the interval [a0,b0]=[-2.4, -1.6]. Also, describe the type of converge/divergence.




































4. (15 pts) The Newthon method works by approximating the function f(x) = 0 using a line at the point xk-1 and the first derivative. Write an improved method to determine xk that approximates f(x) using a parabola that passes through the points xk-1 and x k-2, and uses the first and second derivative. If the iteration equation gives more than one root, choose xk to be the closest root to xk-1. Write the iteration equation for this method.

























5. (15 pts) Solve the following system of linear equations using gaussian elimination.

 x1 + 2x2 + 0x 3 -  x4 = 9

2x1 + 3x2 -  x3 + 0x 4 = 9

0x1 + 4x2 + 2x3 - 5x4 = 26

5x1 + 5x2 + 2x3 + 4x4 = 32

































6. (10 pts.) Use both the Gauss-Seidel and the Jacobi iteration methods to find (xk,yk) for k = 1, 2, 3. Start at the point (x0,y0)=(0,0). Choose iteration equations that will make the method converge.

-x +3y = 1
6x -2y = 2









































7. (10 pts.) Let f(x)= 2sin(3.14x/6), where x is in radians. Use quadratic Lagrange interpolation based on the nodes x0=0, x 1=1, and x2=3 to approximate f(4) 





































8. (10 pts.) Given the following table, compute the divided-difference table for the function x1/2. Also, write down the Newthon polynomials P1(x), P2(x), and P3(x).


k
xk
f(xk)
0
4.0
2.00000
1
5.0
2.23607
2
6.0
2.44949
3
7.0
2.64575






























9. (10 pts.) Using Pade' approximations, find R2,2(x) for f(x)=arctan(x1/2)/x1/2. Start with the Maclaurin expansion: 

f(x)=1 - x/3 + x2/5 - x3/7 + x4/9