ENGR 3

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• Desktop-->Classes-->Matlab-Engineering-->matlab_using_engineering_toolkits.bat

• From Here to Christmas:– Homework 4 is due November 25, Tuesday, 5pm– No office hours next week except Mon 1-5pm in HFH

1111 and Tuesday 2-5pm in Phelps 1530– After Thanksgiving all office hours will be in Phelps 1530– No class on this coming Wednesday– When you come back from Thanksgiving, you will be

only 8 or 10 days away from the Final Exam!– We will review for the final exam similarly to the

midterm. The average score for my sections was much higher than the class average.

• MATLAB !

• MATLAB !

• MATLAB !

• Homework 4– Question 1: Use the MATLAB help files.– Question 2: Very similar to the C programs you’ve

been writing. Hint: consider the commandsfilehandle=fopen(‘testing123.txt’,’w’)fprintf(filehandle,’testing, 1, 2, %d’,7)fclose(filehandle)

– Question 3: Transcendental equation? What!?

• Transcendental Equations:– How would you solve tan(x)=(x-2)2 ?• Sqrt(tan(x))+2=x, nope• x=arctan((x-2)2), nope• Algebra cannot solve this

• Transcendental Equations:– How would you solve tan(x)=(x-2)2 ?• Sqrt(tan(x))+2=x, nope• x=arctan((x-2)2), nope• Algebra cannot solve this

– But computers can!• Plot both sides of the equation and see where they are equal.

• Transcendental Equations:– How would you solve tan(x)=(x-2)2 ?• Sqrt(tan(x))+2=x, nope• x=arctan((x-2)2), nope• Algebra cannot solve this

– But computers can!• Plot both sides of the equation and see where they are equal.

• Transcendental Equations:– How would you solve tan(x)=(x-2)2 ?• Sqrt(tan(x))+2=x, nope• x=arctan((x-2)2), nope• Algebra cannot solve this

– But computers can!• Plot both sides of the equation and see where they are equal.• Tell the computer to loop through many values of x. Compute

both sides of the equation for each of these values of x. Tell the computer to remember the value of x for which the two sides of the equation were closest, kinda like FindPi.c in Homework 3.

• Transcendental Equations:– How would you solve tan(x)=(x-2)2 ?• Sqrt(tan(x))+2=x, nope• x=arctan((x-2)2), nope• Algebra cannot solve this

– But computers can!• Plot both sides of the equation and see where they are equal.• Tell the computer to loop through many values of x. Compute

both sides of the equation for each of these values of x. Tell the computer to remember the value of x for which the two sides of the equation were closest, kinda like FindPi.c in Homework 3.• What range of values should the computer search for? Luckily,

Homework 4 tells you to limit the search to [0,pi/L]

• Ok, Homework 4, ready, set, go!