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 # fuel cost calculator   
 # written on Windowws XP on eTCL 
 # working under TCL version 8.5.6 and eTCL 1.0.1 
 # gold on TCL WIKI , 16aug2010
 frame .frame -relief flat -bg aquamarine4
 pack .frame -side top -fill y -anchor center

 set names {{} {daily_km:} {gas_tank_liters:} {day_fillup:} {cost_per_liter:} {cost_per_km:} {cost_per_km:} {answer cost/km:}}
 foreach i {1 2 3 4 5 6 7} {
   label .frame.label$i -text [lindex $names $i] -anchor e
   entry .frame.entry$i -width 35 -textvariable side$i
   grid .frame.label$i .frame.entry$i -sticky ew -pady 2 -padx 1
 }

 proc about {} {
   set msg "Calculator for fuel cost\nfrom TCL WIKI,\nwritten on eTCL "
   tk_messageBox -title "About" -message $msg
 }

 proc pi {} {expr acos(-1)}
   
 proc interlinear { xx1 yy1 xx3 yy3 xx2 } {
     return [expr {  ((($xx2-$xx1)*($yy3-$yy1))/($xx3-$xx1))+ $yy1 } ] }

 proc pol { xx1 yy1 xx3 yy3 xx2 } {
     return [expr {  ((($xx2-$xx1)*($yy3-$yy1))/($xx3-$xx1))+ $yy1 } ] }
     
 proc errorx  {aa bb} {expr { $aa > $bb ?   (($aa*1.)/$bb -1.)*100. : (($bb*1.)/$aa -1.)*100.}}
   
 proc strat5 { xx1 } {
   global side1 side2 side3 side4 side5 side6 side7
   set ss side1
   set tt $side2
   set side4 [ expr { $side5*1.            } ] 
   set side5 [ expr { $side2*$side4/$side1 } ] 
   set side6 [ expr { $side2*$side4/$side1 } ] 
   set side7 [ expr { $side2*$side4/$side1 } ]
   set side7 [ expr { $side2*$side4/$side1 } ]
   return $side7
 }

 proc calculate {} {
   global colorwarning
   global colorback
   global answer2   answer3
   global side1 side2 side3 side4 side5 side6 side7
   set answer2 5
   set answer2  [ strat5  $side1     ] 
   set side6 $answer2  
 }

 proc fillup {aa bb cc dd ee ff gg} {
   .frame.entry1 insert 0 "$aa"
   .frame.entry2 insert 0 "$bb"
   .frame.entry3 insert 0 "$cc"
   .frame.entry4 insert 0 "$dd"
   .frame.entry5 insert 0 "$ee"
   .frame.entry6 insert 0 "$ff "
   .frame.entry7 insert 0 "$gg "
 }

 proc clearx {} {
   foreach i {1 2 3 4 5 6 7} {
     .frame.entry$i delete 0 end
   }
 }

 proc reportx {} { 
   console show;
   puts "
   The interpolation function takes 
   two known points on a line and
   solves for an intermediate point.
   The points are xx1,yy1 xx2,yy2 and xx3,?yy3?
   The input order of the five items
   is xx1 yy1 xx2 yy2 xx3 
   and solving for ?yy3?.
   The interpolation function loaded as
   proc pol. User should be able to write
   pol 50. 1000. 200. 1200. 150.
   and save answer (1133.3)  on console."
 }

 frame .buttons -bg aquamarine4
    
 ::ttk::button .calculator -text "Solve"     -command calculate
 ::ttk::button .test2      -text "Testcase1" -command {clearx;fillup 50. 15. 2. 3.1  15. 5. 40.}
 ::ttk::button .test3      -text "Testcase2" -command {clearx;fillup 100. 1. 4. 5.2 15. 5. 40.}
 ::ttk::button .test4      -text "Testcase3" -command {clearx;fillup 1000. 1. 5. 6.4 15. 5. 40.}
 ::ttk::button .clearallx  -text clear       -command clearx
 ::ttk::button .about      -text about       -command about
 ::ttk::button .cons       -text report      -command reportx
 ::ttk::button .exit       -text exit        -command exit

 pack .calculator -in .buttons -side top -padx 10 -pady 5
 pack .clearallx .cons .about .exit .test4 .test3 .test2 -side bottom -in .buttons
 grid .frame .buttons -sticky ns -pady {0 10} 
 . configure -background aquamarine4 -highlightcolor brown -relief raised -border 30
 bind . <Motion> {wm title . "fuel cost calculator"}

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