<< Some Fortran compilers have SIN, COS, ATAN etc for radians and SIND, COSD, ATAND etc for degrees; that is convenient (and Fortran users without such compilers can easily write their own modules to include them, and the standard constant pi which Algol 68 has but no Fortran compiler that I have ever met does.) >>
Which is a source of error. I worked on an old subroutine library which included "smooth" versions of step functions. A user reported problems with one of these and when I investigated it appeared the supposed step function was uniformly zero - because the calculation relied on a function SIN (PI*X) and PI was undefined! The danger with using "meaningful" variable names in programming is that they lead one subconsciously to believe that the variable has the value it "says" it has, so that errors like this slip through.