(floor n) should be (ceiling n)

[dwayne]

(define (ceiling->exact n)
  (inexact->exact (floor n)))

See

sicp/sicp-pict/mit-support.scm

Line 16 in 62e7e0d

(define (ceiling->exact n)

.

[sorawee]

Thank you! It's indeed wrong, but we switched to a new implementation of sicp-pict recently, so the bug is a dead code right now. I will delete the file soon, so there's no need to fix it.