Error: (in limit) invalid directional argument

The limit command has an optional third argument, which allows the calculation of various types of limits, e.g. one-sided limits. The allowed values for this argument are left , right , real and complex . Anything else produces this error message. One way this error sometimes arises is if you use left or right as a variable and assign it a value.

Examples:

> limit(2^(1/x), x=0, left);

> limit(2^(1/x), x=0, LEFT);

Error, (in limit) invalid directional argument

Assigning a value to left causes errors:

> left:= 4:

> limit(2^(1/x), x=0, left);

Error, (in limit) invalid directional argument

See also: limit

Maple Advisor Database R. Israel, 1997