remove private example code

Author: doraneko94

examples/tridiagonal.rs

@@ -27,8 +27,4 @@ fn factorize() -> Result<(), error::LinalgError> {
 fn main() {
     solve().unwrap();
     factorize().unwrap();
-    match arr2(&[[0.0]]).extract_tridiagonal() {
-        Ok(_) => {}
-        Err(err) => println!("{}", err),
-    }
 }