The DrawInv command draws the inverse of a curve in terms of X. Its single argument is an expression in terms of X.
For example, DrawInv X2 will draw the inverse of the equation Y=X2. The inverse reverses the variables X and Y, so that the curve X=Y2 will be graphed.
You can also think of this as graphing the expression but with X representing the vertical direction, and Y representing the horizontal.
When evaluating the expression using DrawInv, the calculator will ignore the following errors: ERR:DATA TYPE, ERR:DIVIDE BY 0, ERR:DOMAIN, ERR:INCREMENT, ERR:NONREAL ANS, ERR:OVERFLOW, and ERR:SINGULAR MAT. If one of these errors occurs, the data point will be omitted.
For this reason, DrawInv can sometimes behave in an unexpected fashion: for example, it doesn't throw an error for list or matrix expressions (it won't graph anything, either).