started tracking t_est[] and t_up[];

refactored code, moving math from ck_uptime() to BEGIN block;
switched to using t_up(new) = t_up(old) + dt to predict uptime;
added conditional use of "date +%s.%N" to get t as float on FreeBSD;
merged some changes between ckt0.awk and ckcptime.awk;

1 files changed, 16 insertions, 44 deletions

diff --git a/ckcptime.awk b/ckcptime.awk
index e6c88d1..7bfef6e 100644
--- a/ckcptime.awk
+++ b/ckcptime.awk
@@ -8,12 +8,7 @@ function log10(n) {
 
 function merge_meas(est_val, est_unc, meas_val, meas_unc) {
 
-    # add (meas - est) delta to the measurement uncertainty
-    # note: this works when tracking a constant value,
-    # the first derivative of a constant 'should' be zero
-    # unc_meas = sqrt(unc_meas^2.0 + (val_meas - val_est)^2.0)
-
-    # Kalman filtering compares variances
+    # Kalman filtering compares variances,
     # convert uncertainties to square units
     est_unc = (0.5*est_unc)^2.0
     meas_unc = (0.5*meas_unc)^2.0
@@ -35,14 +30,17 @@ function sigfig(val, unc) {
     ordmag_val = log10(val)
     ordmag_unc = log10(unc)
 
-    #sigfig_unc = sprintf("%.f", 6)
-    sigfig_unc = sprintf("%.f", sqrt((ordmag_val - ordmag_unc)^2.0) + 1.0)
-    sigfig_val = sprintf("%.f", (ordmag_val - ordmag_unc + sigfig_unc))
+    ordmag_high = sqrt((ordmag_val)^2.0 + (ordmag_unc)^2.0)
+    ordmag_low = ((ordmag_val)^-1.0 + (ordmag_unc)^-1.0)^-1.0
+    ordmag_range = ordmag_high - ordmag_low
+
+    sigfig_unc = sprintf("%.f", sqrt((ordmag_range)^2.0 + 3.0^2.0))
+    sigfig_val = sprintf("%.f", sqrt((ordmag_range)^2.0 + (sigfig_unc)^2.0 + 3.0^2.0))
 
     ofmt_val = "%." sigfig_val "g"
     ofmt_unc = "%." sigfig_unc "g"
 
-    return sprintf(ofmt_val OFS ofmt_unc ORS, val, unc)
+    return sprintf(ofmt_val OFS ofmt_unc, val, unc)
 
 }
 
@@ -66,20 +64,12 @@ function ck_cptime() {
 }
 
 
-function ck_uptime(t0_est, t0_unc) {
-
-    t_sys_meas[1] = systime()
-    t_sys_meas[2] = 1.0
+function ck_uptime() {
 
+    # check uptime cmd
     "uptime" | getline t_up_cmd
     close("uptime")
 
-    split(merge_meas(t_sys_meas[1], t_sys_meas[2], systime(), 1.0), t_sys_meas)
-
-    # estimate (predict) uptime
-    t_up_est[1] = t_sys_meas[1] - t0_est
-    t_up_est[2] = t_sys_meas[2] + t0_unc
-
     # evaluate measured uptime
     t_up_meas[1] = 0.0
     t_up_meas[2] = systime()
@@ -119,38 +109,20 @@ function ck_uptime(t0_est, t0_unc) {
 
     }
 
-    # merge predicted and measured uptimes
-    split(merge_meas(t_up_est[1], t_up_est[2], t_up_meas[1], t_up_meas[2]), t_up_est)
-
-    # evaluate measured boot time, t0
-    t_boot_meas[1] = t_sys_meas[1] - t_up_meas[1]
-    t_boot_meas[2] = t_sys_meas[2] + t_up_meas[2]
-
-    # merge previous and updated boot time, t0
-    split(merge_meas(t0_est, t0_unc, t_boot_meas[1], t_boot_meas[2]), t_boot_est)
-
-    return sigfig(t_boot_est[1], t_boot_est[2])
+    return sigfig(t_up_meas[1], t_up_meas[2])
 
 }
 
 
 BEGIN {
 
-    OFMT="%.21g"
+    OFMT="%f"
+    pi = 4.0*atan2(1.0, 1.0)
+    c0 = 299792458  # m/sec
+
     #print("_systime_", systime())
     #print("_boottime_", ck_boottime())
-    printf("%s" ORS, ck_cptime())
-
-    # check ARGV for previous estimate
-    # if (ARGC > 0) {
-    #     ARGV[1] ? t0_est[1] = ARGV[1] : t0_est[1] = 0.0
-    #     ARGV[2] ? t0_est[2] = ARGV[2] : t0_est[2] = systime()
-    # }
-    #print("t0_est = ", t0_est[1])
-    #print("t_boot_unc = ", t0_est[2])
-
-    # check uptime, update estimate
-    #print(ck_uptime(t0_est[1], t0_est[2]))
+    print( ck_cptime() )
 
 }