Principal Branches of Inverse Trigonometric and Inverse Hyperbolic Functions

We discuss principal branches for five square root functions and for the inverse trigonometric and inverse hyperbolic functions. We take the standard reference in this area to be the NIST Digital Library of Mathematical Functions (DLMF). We adopt the notation for and the definitions of the principal branches of the inverse functions in the DLMF. Similarly, the branch cuts for the inverse functions are defined as per the DLMF. Our goal is to use complex analysis to turn the definitions of the principal branches in the DLMF into concrete expressions that hold on the entirety of their respective cut planes. The square root principal branch expressions are new breakthrough discoveries that lead smoothly to four of the concrete expressions. We expand the number of concrete expressions in Sections 4.23 and 4.37 in the DLMF from two to eight. Three of these eight concrete expressions were in print in 1924. One of the latter is still awaiting inclusion in the DLMF. Taken altogether, we provide a computationally efficient resource for computer algebra in programming languages, specifically for the principal branches of the inverse trigonometric and inverse hyperbolic functions.