A bit more Newtonian physics :-)

1 files changed, 19 insertions, 0 deletions

diff --git a/free-fall.lsp b/free-fall.lsp
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+;; TODO: air resistance, terminal velocity
+(defconstant +G+ 9.81)
+(defglobal *alt* 20000)
+(defglobal *v* 0)
+(defun step ()
+   (setq *alt* (- *alt* *v*))
+   (setq *v* (+ *v* +G+))
+   (format (standard-output) "~A~%" *alt*))
+(defun my-main ()
+   (while (> *alt* 0)
+	  (step)))
+
+;;; And here's an example from GNAT:
+(defun free-fall ()
+   (format (standard-output) "Gravitational constant: ~A~%" +G+)
+   (format (standard-output) "Twice that: ~A~%" (* 2 +G+))
+   (let* ((time 10)
+          (distance (* 0.5 +G+ (expt time 2))))
+         (format (standard-output) "Distance travelled in 10 seconds of free fall: ~A~%" distance)))