How does Matlab represent individuals and design variables in GA?

Hello,

I'm reading the Matlab GA documentation and something is not very clear to me. How does Matlab represent individuals and design variables?

As I know, standard genetic algorithms represent a design variable by a vector containing binary numbers. For example, if the variable 'a' ranges from 0 to 1 and we use 2 binary numbers to represent it, a = 0.66 is computed as a = [1 0]. Moreover, an individual is represented by a list of those vectors of binary numbers.

However, from the Matlab user's guide, it seems that the design variables are represented by a float number, in other words, in the previous example, 'a' would be simply 0.66. Is that right or I got it wrong?