1. Chp3 Tutorial: Prob 3.15 Solution
Engineering 25
Chp3 Tutorial: Prob 3.15 Solution
Bruce Mayer, PE
Licensed Electrical & Mechanical Engineer

4. 4

5. Quick Solve by Anon
Use Anonymous Function to very Quickly Solve for rmin

6. fminbnd Command
fminbnd finds the minimum of a function of one variable within a fixed interval.
Syntax for this case
[x,fval] = fminbnd(fcn,x1,x2)
[x, fval] = fminbnd(fcn,x1,x2) returns a value x that is a local minimizer; i.e., xmin. of the function that is described in fcn over the interval x1 < x< x2.
fval is the minimum value of the function for the corresponding minimizing x; that is fval = fcn(xmin).

7. The Function File
area3_15.m

8. The Command Session

9. The Sensitivity Plot +10% on Amin r →  1.49 – 2.35 in
~21.37
~1.49
~2.35
+10% on Amin
Amax = 1.1* = in2
r →  1.49 – 2.35 in

10. Comments The 10% increase in Amin Results in These Changes for rmin
-23% for rlo
+24% for rhi
Thus The change in Area is less than half the change in r.
A is NOT very Sensitive About the Minimum Point