Some work undertaken with a ClassPad leads users to define x as a specific ‘thing’, maybe a matrix or a real or complex number. This definition is retained by the ClassPad until we “clear all variables”. This means that if we attempt to work with x as a variable, when it has been defined previously, unexpected errors and outputs are likely to occur.

To “clear all variables”, when in Main, tap Edit and Clear All Variables.

To check if there is an issue with x (or any other variable you wish to use), input x (in Main). The output should be x if it is to be used as a variable.