Logarithm at minus 1

Theorem

The following formula holds: $$\log(-1)=\pi i,$$ where $\log$ denotes the logarithm, $\pi$ denotes pi, and $i$ denotes the imaginary number.

References

• 1964: Milton Abramowitz and Irene A. Stegun: Handbook of mathematical functions ... (previous) ... (next): $4.1.14$