If xi is a file, subsequent output is to xi. Initial output is to standard error output. Produces the tangent of r1 given in radians. It fails if there is no such position. Produces the variable for the identifier or keyword named s, but fails if there is no such variable.
Local identifiers override global identifiers.
Produces the current byte position in f. The first byte in the file is at position 1. If xi is a file, subsequent output is to xi. Initial output is to standard output. If xi is a file, subsequent output is to xi.