Internal function used to check the validity of inputs.
check_input(x)# S3 method for default
check_input(x)
# S3 method for numeric
check_input(x)
# S3 method for double
check_input(x)
# S3 method for matrix
check_input(x)
# S3 method for xts
check_input(x)
# S3 method for tbl_df
check_input(x)
A matrix
Any object passed to other functions in the package.