Here the IC is wired as a boost converter where resistors R1 and R2 are used to set the output voltage .The junction of R1 and R2 is connected to the feedback pin of IC1. Where ever positive and negative voltages are required like analog circuits Zero volt which is the reference for indicating positive and negative voltages, is taken as common and ground. LM2585 is a monolithic integrated voltage converter IC that can be used in various applications like flyback converters, boost converters, forward converters, multiple output converters etc.
The circuit requires minimum number of external components and the IC can source up to 3A output current. To avoid too many connection and making the circuit simple with clarity i8t is shown this way and it is a standard way of presenting.