# fluid-set-boundary   xtlang

##### Implementation

```(bind-func fluid-set-boundary
(lambda (b:i64 x:double* N:i64)
(let ((j 0)
(i 0)
(kk 0)
(ii 0)
(kkk 0)
(jjj 0))
(dotimes (j (- N 2))
(dotimes (i (- N 2))
(pset! x (fluid-ix (+ i 1) (+ j 1) 0 N)
(if (= b 3)
(- 0.0 (pref x (fluid-ix (+ i 1) (+ j 1) 1 N)))
(pref x (fluid-ix (+ i 1) (+ j 1) 1 N))))
(pset! x (fluid-ix (+ i 1) (+ j 1) (- N 1) N)
(if (= b 3)
(- 0.0 (pref x (fluid-ix (+ i 1) (+ j 1) (- N 2) N)))
(pref x (fluid-ix (+ i 1) (+ j 1) (- N 2) N))))))
(dotimes (kk (- N 2))
(dotimes (ii (- N 2))
(pset! x (fluid-ix (+ ii 1) 0 (+ kk 1) N)
(if (= b 2)
(- 0.0 (pref x (fluid-ix (+ ii 1) 1 (+ kk 1) N)))
(pref x (fluid-ix (+ ii 1) 1 (+ kk 1) N))))
(pset! x (fluid-ix (+ ii 1) (- N 1) (+ kk 1) N)
(if (= b 2)
(- 0.0 (pref x (fluid-ix (+ ii 1) (- N 2) (+ kk 1) N)))
(pref x (fluid-ix (+ ii 1) (- N 2) (+ kk 1) N))))))
(dotimes (kkk (- N 2))
(dotimes (jjj (- N 2))
(pset! x (fluid-ix 0 (+ jjj 1) (+ kkk 1) N)
(if (= b 1)
(- 0.0 (pref x (fluid-ix 1 (+ jjj 1) (+ kkk 1) N)))
(pref x (fluid-ix 1 (+ jjj 1) (+ kkk 1) N))))
(pset! x (fluid-ix (- N 1) (+ jjj 1) (+ kkk 1) N)
(if (= b 1)
(- 0.0 (pref x (fluid-ix (- N 2) (+ jjj 1) (+ kkk 1) N)))
(pref x (fluid-ix (- N 2) (+ jjj 1) (+ kkk 1) N))))))
```