## Friday, 3 January 2014

### Complex numbers

I stumbled upon an unadvertised feature in the generate attributes and generate macro operators in RapidMiner Studio 6. It's possible to use the square root of -1, denoted by the reserved symbol i, in the function expressions when creating attributes and macros. There are also some new functions:

• re()
• im()
• conj()
Use of a complex number to generate an attribute results in the real part being used only whereas generating a complex macro like this

CN = -3+2*i

results in a macro value that looks like this:

(-3.0, 2.0)

This would be -3+2i.

Can a macro, once created, be used as an argument to create other macros or attributes?

The answer is no but there is some fiddling around that can make some things work.

If my macro is generated like this

CN = -3+2*i

I can create another macro like this

CN_1 = replace("%{CN}", ", ", "+i*")

I then get this value for CN_1

(-3+i*2)

I can then put this result in an attribute as a string. I can also use functions like re() and abs() directly on this so for example I can create an attribute like this (note that I am passing a string to the abs function that happens to be a valid complex number)

CNLen = abs(%{CN_1})

Sure enough, the attribute contains the expected value of 3.606.

I'm not sure if this is a taste of things to come or whether it's unintended. I suppose it would be cool to have the ability to manipulate complex numbers.