The set data command changes the effective size of vectors. All the vector arithmetic checks for index boundaries. The data constant is the higher bound of the check and necessarily the size of all vectors. Changing the data value does not change the values nor the capacity of vectors. It only changes the upper bound on the value the index can take. The data constant is also changed by the commands read and exec, which set it to the number of valid data points read. Because the upper bound can never be higher than the effective capacity of vectors, a data value higher than the current samples value will be refused. See set samples. Typically, set data is used when one wants the C-calculator to generate (and plot) vectors. The read and exec commands take care of adjusting it. data constant can also be changed from the C-calculator mode if the constant is unlocked. However, no check is made to ensure the given value is not higher than sample size, in which case a segmentation fault will crash the whole program. It is always safer to use set data.
set data number
set data 300
lock, unlock, read, exec, cmode