Sorting is by keys for i odd, by value for i even. However, among lists and among records, two structures are ordered by comparing their ith fields. Two structures having the equal ith fields are ordered as they would be in regular sorting, but structures lacking an ith field appear before structures having them. Produces the square root of r1. 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.