**//Functions of a real variable//**

Mathematical functions of single real variable. Will accept any integer of float atom. For the variable out of domain, these functions return ''NIL''.

Trigonometric functions sine ''SIN'', cosine ''COS'', secant ''SEC'', cosecant ''CSC'', tangent ''TAN'', cotangent ''COT''.

Versions expecting angle in degrees: ''SIN-D'', ''COS-D'', ''SEC-D'', ''CSC-D'', ''TAN-D'', ''COT-D''.

Inverse functions returning radians: ''ASIN'', ''ACOS'', ''ASEC'', ''ACSC'', ''ATAN'', ''ACOT''.

Their modifications returning degrees: ''ASIN-D'', ''ACOS-D'', ''ASEC-D'', ''ACSC-D'', ''ATAN-D'', ''ACOT-D''.

Square ''SQR'', and square-root ''SQRT''. 

Exponential function ''EXP'', with base the Euler's number. Natural logarithm ''LN''.

Exponential function ''10POW'', with base 10. Decimal logarithm ''LOG''.

Absolute value ''ABS''.