Re: Floating Point computations in elisp

[Emanuel Berg]

> How can I do floating point computations in elisp
>
> (setq frc (/ tpd 60.0))

As you did, just add a .0 to avoid integer division.

Other than that, just compute whatever you like.

(defun mean-value (vs)
  (let*((sum  (apply #'+ vs))
        (mean (/ sum (length vs) 1.0)) )
    mean) )

(defun hypotenuse (c1 c2)
  (sqrt (+ (* c1 c1) (* c2 c2))) )

(defun speed (hour minute second km)
  (let*((s (+ second (* 60 minute) (* 60 60 hour)))
        (m (* 1000 km))
        (mps (/ m s)) )
    (* 3.6 mps) ))

Hm ... what does that do?

Anyway, you can then use `format' to - that's right - format
the output. It is very versatile, see the docstring.

(defun compute-space-distance (dist num-beams beam-width)
  (let*((spaces         (1+ num-beams))
        (dist-covered   (* num-beams beam-width))
        (dist-uncovered (- dist dist-covered))
        (space          (/ dist-uncovered spaces 1.0) ))
    space ))

;; (insert (format "\n;; %.2f" (compute-space-distance 262 16 12)))
;; 4.12

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