From: rearman <rearman@r717.net>
Date: Wed, 2 Nov 2022 13:17:11 +0000 (-0400)
Subject: Revert "Delete work-eqs.el"
X-Git-Url: https://git.earman.xyz/?a=commitdiff_plain;h=4f058122f4240e16104a2c89aac3a34ad5753fdb;p=emacsinit.git

Revert "Delete work-eqs.el"

This reverts commit ba6df08405fc579f414aea82123aa50fea89faa2.
---

diff --git a/work-eqs.el b/work-eqs.el
new file mode 100644
index 0000000..ce37016
--- /dev/null
+++ b/work-eqs.el
@@ -0,0 +1,55 @@
+;; WORK (NON-EDITING) RELATED DEFUNS
+(defun square (x)
+  "Calculate the square of a value."
+  (expt x 2))
+
+(defun cube (x)
+  "Calculate the cube of a value."
+  (expt x 3))
+
+(defun scaleval (pmax pmin emax emin &optional ai)
+  "Calculate the slope and offset given PLC Max/Min and Eng. Max/Min.
+With optional argument 'ai', also calculate a final scaled value from an input."
+  (let ((div (/ (- pmax pmin) (- emax emin))))
+    (let ((ofst (- emin (/ pmin div))))
+      (if (not (eq nil ai))
+	  (let ((final (+ ofst (/ ai div))))
+	    (list div ofst final))
+	(list div ofst)))))
+
+(defun cfm-circ (fpm radius)
+  "Calculate the CFM of a circular duct given fpm and radius (in)."
+  (list (* pi fpm (square (/ radius 12)))))
+
+(defun cfm-rect (fpm width height)
+  "Calculate the CFM of a circular duct given fpm, width (in) and height (in)."
+  (list (* fpm (/ width 12) (/ height 12))))
+
+(defun pid-tune (Ku Tu p-type)
+  "Use the Ziegler-Nichols method to tune a P, PI or PID loop.
+Takes Ku, Tu and p-type (P, PI, or PID) as arguments, and returns appropriate kp, ki, and kd."
+  (cond ((or (equal 'p p-type)
+	     (equal 'P p-type))
+	 (list (* 0.5 Ku)))
+	((or (equal 'pi p-type)
+	     (equal 'PI p-type))
+	 (list (* 0.45 Ku) (/ (* 0.54 Ku) Tu)))
+	((or (equal 'pid p-type)
+	     (equal 'PID p-type))
+	 (list (* 0.6 Ku) (/ (* 1.2 Ku) Tu) (/ (* 3.0 Ku Tu) 40)))))
+
+(defun gn-water-per-lb (temp humidity)
+  "Calculate the grains of water per lb of air, given temperature (F) and humidity (%).
+Returns a list of Sat. Water Press., Hum. Ratio, and Gns Moisture/lb air."
+  (let ((sat-water-press (+ .0182795
+			    (* temp .001029904)
+			    (* (square temp) 0.00002579408)
+			    (* (cube temp) (* 2.400493 (expt 10 -7)))
+			    (* (expt temp 4) (* 8.100939 (expt 10 -10)))
+			    (* (expt temp 5) (* 3.256805 (expt 10 -11)))
+			    (* (expt temp 6) (* -1.001922 (expt 10 -13)))
+			    (* (expt temp 7) (* 2.44161 (expt 10 -16))))))
+    (let ((hum-press (* (/ humidity 100.0) sat-water-press)))
+      (let ((hum-ratio (/ (* hum-press 0.62198) (- 14.7 hum-press))))
+	(let ((gns-mstr-lb-air (* hum-ratio 7000)))
+	  (list sat-water-press hum-ratio gns-mstr-lb-air))))))