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authorjoshuab <>2010-06-29 15:20:25 +0000
committerbnewbold <bnewbold@adelie.robocracy.org>2010-06-29 15:20:25 +0000
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parentd8ea24df5c729ddbd2d9e84402e2c0db82c6be29 (diff)
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tex
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@@ -70,20 +70,20 @@ projections onto the real and imaginary axis. If we use column vector
notation, we have
$z = \left(\begin{array}{c}
a\\
-b\end{array}\right)\\
+b\end{array}\right)
= a\left(\begin{array}{c}
1\\
0\end{array}\right)+b\left(\begin{array}{c}
0\\
-1\end{array}\right)\\
- = a\cdot1+b\cdot i\\
+1\end{array}\right)
+ = a\cdot1+b\cdot i
= a+bi$
Put another way, we are using $1$ and $i$ as basis vectors. For
-example,
+example,
$\left(\begin{array}{c}
3\\
-2\end{array}\right)=3(\rightarrow)+2(\uparrow)=3+2i$
-and
+2\end{array}\right)=3(\rightarrow)+2(\uparrow)=3+2i$
+and
$\overset{2}{\nwarrow}=\left(\begin{array}{c}
-\sqrt{2}\\
\sqrt{2}\end{array}\right)=-\sqrt{2}(\rightarrow)+\sqrt{2}(\uparrow)=-\sqrt{2}+\sqrt{2}i$
@@ -93,8 +93,8 @@ Polar coordinates represent each complex number by its magnitude and argument, i
$i=\uparrow=(1,\pi/2)$ and $\overset{2}{\nwarrow}=(2,3\pi/4)$.
The familiar angle addition formula from trigonometry now follows
-from the distributive law applied to unit vectors.
-$\cos(\theta+\phi)+i\sin(\theta+\phi)=(\cos\theta+i\sin\theta)(\cos\phi+i\sin\phi)=\cos\theta\cos\phi-\sin\theta\sin\phi+i(\cos\theta\sin\phi+\sin\theta\cos\phi)$
+from the distributive law applied to unit vectors.
+ $\cos(\theta+\phi)+i\sin(\theta+\phi)=(\cos\theta+i\sin\theta)(\cos\phi+i\sin\phi)=\cos\theta\cos\phi-\sin\theta\sin\phi+i(\cos\theta\sin\phi+\sin\theta\cos\phi)$
In the workshop session, you'll use a similar trick to compute triple
@@ -139,8 +139,8 @@ As a sanity check, note that $i$ corresponds to $\left(\begin{array}{cc}
0 & -1\end{array}\right)\sim-1$.
Another natural transformation of the complex plane is given by squaring,
-sending $z\rightsquigarrow z^{2}$. This squares the length of each
-vector, and doubles its angle. PICTURE. What does $z\rightsquigarrow z^{n}$
+sending $z\mapsto z^{2}$. This squares the length of each
+vector, and doubles its angle. PICTURE. What does $z\mapsto z^{n}$
look like? PICTURE.
Another key example is the exponential map. Recall the power series