Complex Logarithm
1. The problem is to find the value of $$z = \frac{\log(1+i)}{1-i}$$ where $i$ is the imaginary unit with $i^2 = -1$.
2. Recall that $\log$ of a complex number $z = re^{i\theta}$ (in polar form) is given by $$\log z = \log r + i\theta$$ where $r = |z|$ and $\theta = \arg(z)$.
3. First, find $1+i$ in polar form:
- Magnitude: $$r = |1+i| = \sqrt{1^2 + 1^2} = \sqrt{2}$$
- Argument: $$\theta = \tan^{-1}\left(\frac{1}{1}\right) = \frac{\pi}{4}$$
4. So, $$\log(1+i) = \log\sqrt{2} + i\frac{\pi}{4} = \frac{1}{2}\log 2 + i\frac{\pi}{4}$$
5. Next, simplify the denominator $1 - i$ by multiplying numerator and denominator by the conjugate $1 + i$:
$$\frac{\log(1+i)}{1-i} \times \frac{1+i}{1+i} = \frac{\log(1+i)(1+i)}{(1-i)(1+i)}$$
6. Calculate the denominator:
$$(1-i)(1+i) = 1 - i^2 = 1 - (-1) = 2$$
7. Calculate the numerator:
$$\log(1+i)(1+i) = \left(\frac{1}{2}\log 2 + i\frac{\pi}{4}\right)(1+i)$$
8. Multiply out:
$$= \frac{1}{2}\log 2 \times 1 + \frac{1}{2}\log 2 \times i + i\frac{\pi}{4} \times 1 + i\frac{\pi}{4} \times i$$
$$= \frac{1}{2}\log 2 + i\frac{1}{2}\log 2 + i\frac{\pi}{4} + i^2 \frac{\pi}{4}$$
9. Since $i^2 = -1$, this becomes:
$$= \frac{1}{2}\log 2 + i\frac{1}{2}\log 2 + i\frac{\pi}{4} - \frac{\pi}{4}$$
10. Group real and imaginary parts:
$$= \left(\frac{1}{2}\log 2 - \frac{\pi}{4}\right) + i\left(\frac{1}{2}\log 2 + \frac{\pi}{4}\right)$$
11. Divide by denominator 2:
$$z = \frac{1}{2} \left(\frac{1}{2}\log 2 - \frac{\pi}{4}\right) + i \frac{1}{2} \left(\frac{1}{2}\log 2 + \frac{\pi}{4}\right)$$
12. Simplify:
$$z = \frac{1}{4}\log 2 - \frac{\pi}{8} + i \left( \frac{1}{4}\log 2 + \frac{\pi}{8} \right)$$
Final answer:
$$\boxed{z = \frac{1}{4}\log 2 - \frac{\pi}{8} + i \left( \frac{1}{4}\log 2 + \frac{\pi}{8} \right)}$$