I observed the following phenomenon when using R and Matlab.
When I apply log to a negative number in R, I get the following error message:
Warning message: In log(-1) : NaNs produced
However, when I apply log to a negative number in Matlab, I get e.g., the following complex numbers:
log(-1): 0.0000 + 3.1416i
log(-5): 1.6094 + 3.1416i
Is there any way to achieve the same behavior in R? Or is there anything in favor of the default option in R?
log gives you complex when you give it complex in the first place.
log(-1+0i)
# [1] 0+3.141593i
log(-5+0i)
# [1] 1.609438+3.141593i
I don't know why it doesn't give an option to do this by default, but then again I don't work in complex numbers all the time.
If you want to do this programmatically, you can use as.complex:
log(as.complex(-1))
# [1] 0+3.141593i
or even make a helper function simplify it for you:
mylog <- function(x, ...) log(as.complex(x), ...)
mylog(-1)
# [1] 0+3.141593i