# An Ill Omen

While sitting at my desk this morning before driving to campus, I heard a loud whack! at the balcony windows. Fearing they had cracked, I looked to find a bird had flown into it. I spotted just in time to see its death rattle. How dispiriting. It was not how I wanted to start my day.

# New Term and Position

Today is the start of the spring 2015 term at both Ivy Tech and IUPUI. I will have classes at both institutions.

This term I will be a lab assistant for ECE 362, our required microcontroller and assembly programming course.

This is going to be an interesting term!

# Errata for "Getting Started with the TI-89 Graphing Calculator"

Let me start by saying that I have a TI-89 Titanium, so perhaps what I list as errata is not for the TI-89, which differs from the Titanium. Regardless, I am working through Carl Swenson's book Getting Started with the TI-89 Graphing Calculator, quite a good book, but errors pop up now and then. Those that trouble me most follow.

Chapter 13, page 56 has two sum equations that are incorrect. I found the correct forms at TechniCalc. Change the equations to:

$\Sigma(y1(a+i*(b-a)/n)*(b-a)/n,i,0,n-1)\rightarrow lhs(a,b,n)$
$\Sigma(y1(a+i*(b-a)/n)*(b-a)/n,i,1,n)\rightarrow rhs(a,b,n)$

The commands in Figure 13.3 will now work.

Chapter 16, page 68 has code for a program called rsum() that will not work as written. To make it work, omit the final 1 in each summation command; that is, not
$\Sigma(y1(xmin+i*d),i,0,n-1,1)*d\rightarrow s1$
but
$\Sigma(y1(xmin+i*d),i,0,n-1)*d\rightarrow s1$
Fix all three instances and it will work.

Chapter 19, page 83 has no error but the equation is missing. It is simple enough, but here it is anyway:

$y1(x)=\Sigma(1000*(1.05)^{(i-1)},i,1,x)$

Chapter 21, page 92 needs a second closing parens added to the piecewise equation for y1.

Chapter 24, page 104 has a boxed-in Tip for unlocking the data file. The last value should be 22, not 21.

Chapter 26, page 112 lacks the full equation for the overdamped case. The equation to enter is:

deSolve(y''+3*y'+2*y=0 and y(0)=-.5 and y'(0)=3,t,y)

Chapter 26, page 113 lacks the equation for the Home menu's F2:zeros() command. You can cut and paste from the equation in the history above the entry field then delete the "y=" part, but here it is:

zeros(2.*e^(-t)-2.5*e^(-2*t),t)

Chapter 26, page 114 lacks two equations that are not difficult to figure out; nevertheless, here they are:

deSolve(y''+2*y'+2*y=0 and y(0)=-.5 and y'(0)=3,t,y)
zeros((2.5*sin(t)-.5*cos(t))*e^(-t),t)