**Monthly Car Loan Payments and eTCL demo example calculator, numerical analysis** This page is under development. Comments are welcome, but please load any comments in the comments section at the bottom of the page. Please include your wiki MONIKER in your comment with the same courtesy that I will give you. Its very hard to reply intelligibly without some background of the correspondent. Thanks,[gold] ---- <> [gold] Here is some eTCL starter code for Monthly Car Loan Payments in calculator shell. In planning any software, it is advisable to gather a number of testcases to check the results of the program. The results of the testcases are estimated using the hand calculator and then checked in the eTCL slot calculator. Pseudocode and equations are developed from the hand calculations and theory. Small console programs are written to check or proof the alternate subroutines or procedures, rather than keeping the unblessed code and comment lines in the main slot calculator. Finally the improved or alternate subroutines are loaded into the slot calculator. The eTCL slot calculator is effectively a shell program to input entries, host calculation routines, and display results. Additional significant figures are used to check the eTCL calculator, not to infer the accuracy of inputs and product reports. For the first testcase of sqrt 3, n=2,n*n=4, s=3 was hand calculated in formula. For the second testcase of sqrt 216000, n= For the third testcase of ---- **Pseudocode Section** ====== # using pseudocode for procedure algorithm. 3 quantities needed target number trial_square_root, w.a. guess formula factor , usually 2 or 3 check approx. root from square side rule with sqrt function in TCL ref. errorx procedure check_answer new area =? desired goal , desired goal reached (yes/no) set answers and printout with resulting values ====== ***Testcases Section*** In planning any software, it is advisable to gather a number of testcases to check the results of the program. The math for the testcases can be checked by pasting statements in the TCL console. Aside from the TCL calculator display, when one presses the report button on the calculator, one will have console show access to the capacity functions (subroutines). **** Testcase 1 **** **** Testcase 2 **** **** Testcase 3 **** ***Screenshots Section*** ****figure 1.**** ---- ***References:*** * Daniel F. Mansfield , N.J. Wildberger. ---- **Appendix Code** ***appendix TCL programs and scripts *** ====== # pretty print from autoindent and ased editor # Monthly Car Loan Payments calculator (amortized over loan) # written on Windows XP on eTCL # working under TCL version 8.5.6 and eTCL 1.0.1 # gold on TCL WIKI, 5nov2017 package require Tk package require math::numtheory namespace path {::tcl::mathop ::tcl::mathfunc math::numtheory } set tcl_precision 17 frame .frame -relief flat -bg aquamarine4 pack .frame -side top -fill y -anchor center set names {{} {total loan amount dollars :} } lappend names {number of months:} lappend names {monthly interest rate: } lappend names {answers: intermediate term in formula } lappend names {optional :} lappend names {optional : } lappend names {total loan amount dollars: } lappend names {monthly payments :} foreach i {1 2 3 4 5 6 7 8} { 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 Monthly Car Loan Payments from TCL WIKI, written on eTCL " tk_messageBox -title "About" -message $msg } proc ::tcl::mathfunc::precision {precision float} { # tcl:wiki:Floating-point formatting, [AM] set x [ format "%#.5g" $float ] return $x } #proc errorx always returns a positive error. #Normally assume $aa is human estimate, #assume $bb is divinely exact. proc errorx {aa bb} {expr { $aa > $bb ? (($aa*1.)/$bb -1.)*100. : (($bb*1.)/$aa -1.)*100.}} proc calculate { } { global answer2 global side1 side2 side3 side4 side5 global side6 side7 side8 global testcase_number incr testcase_number set side1 [* $side1 1. ] set side2 [* $side2 1. ] set side3 [* $side3 1. ] set side4 [* $side4 1. ] set side5 [* $side5 1. ] set side6 [* $side6 1. ] set side7 [* $side7 1. ] set side8 [* $side8 1. ] set loan_amount $side1 set number_months $side2 set monthly_interest_rate $side3 set term1 [+ 1. $monthly_interest_rate ] set monthly_payments [/ [* $loan_amount $monthly_interest_rate ] [- 1. [** $term1 [* -1. $number_months ]]]] set side4 $monthly_payments set side7 $loan_amount set side8 [::tcl::mathfunc::precision 4 $monthly_payments ] } proc fillup {aa bb cc dd ee ff gg hh} { .frame.entry1 insert 0 "$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" .frame.entry8 insert 0 "$hh" } proc clearx {} { foreach i {1 2 3 4 5 6 7 8 } { .frame.entry$i delete 0 end } } proc reportx {} { global answer2 global side1 side2 side3 side4 side5 global side6 side7 side8 global testcase_number console show; puts "%|table $testcase_number|printed in| tcl wiki format|% " puts "&| quantity| value| comment, if any|& " puts "&| $testcase_number:|testcase_number | |&" puts "&| $side1 :|total loan amount dollars | |&" puts "&| $side2 :|number of months | |& " puts "&| $side3 :|function factor | |& " puts "&| $side4 :|answers: intermediate term in formula| |&" puts "&| $side5 :|optional | |&" puts "&| $side6 :|optional | |&" puts "&| $side7 :|total loan | |&" puts "&| $side8 :|monthly interest rate | |&" } frame .buttons -bg aquamarine4 ::ttk::button .calculator -text "Solve" -command { set side8 0 ; calculate } ::ttk::button .test2 -text "Testcase1" -command {clearx;fillup 2600. 24.0 0.1 289.0 0.0 0.0 2600.00 289.38} ::ttk::button .test3 -text "Testcase2" -command {clearx;fillup 1000.0 24.0 0.2 202.0 0.0 0.0 1000.00 202.55} ::ttk::button .test4 -text "Testcase3" -command {clearx;fillup 10000.0 24.0 0.2 2025.0 0.0 0.0 10000.00 2025.50} ::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 wm title . "Monthly Car Loan Payments Calculator" ====== ---- *** Pushbutton Operation*** For the push buttons, the recommended procedure is push testcase and fill frame, change first three entries etc, push solve, and then push report. Report allows copy and paste from console. For testcases in a computer session, the eTCL calculator increments a new testcase number internally, eg. TC(1), TC(2) , TC(3) , TC(N). The testcase number is internal to the calculator and will not be printed until the report button is pushed for the current result numbers. The current result numbers will be cleared on the next solve button. The command { calculate; reportx } or { calculate ; reportx; clearx } can be added or changed to report automatically. Another wrinkle would be to print out the current text, delimiters, and numbers in a TCL wiki style table as ====== puts " %| testcase $testcase_number | value| units |comment |%" puts " &| volume| $volume| cubic meters |based on length $side1 and width $side2 |&" ====== ---- ---- ---- [gold] This page is copyrighted under the TCL/TK license terms, [http://tcl.tk/software/tcltk/license.html%|%this license]. **Comments Section** <> Please place any comments here, Thanks. <> Numerical Analysis | Toys | Calculator | Mathematics| Example| Toys and Games | Games | Application | GUI <> Development | Concept| Algorithm | Procedure