functions can only see variables outside their workspace if the variables are declared global or if the function is a nested function and the variable is defined in an outer nesting function. You are defining the variable at the command prompt, outside of any function, so basis1 cannot possibly be a nested function (and nested functions would need an extra 'end' statement in them.)
If you want basis1 to know the value of m, pass m in to basis1.
Why are you bothering to pass any parameters to basis1 if you are going to ignore the parameters inside the function?
Please note that when you call a function with a parameter, the value of the parameter gets transferred in that position and becomes available under the name of the variable in the corresponding position in the "function" line for the function. The name of variables passed as parameters is sometimes available, but never when an expression is passed . So when you call
basis1(n(m-1),n(m),n(m-1))
the value n(m-1) becomes available as x1 inside the function, but the name 'n(m-1)' is not going to be available and n(m-1) cannot be accessed inside the function... but x1 can be.
