**
PAD-Description
End-User License (EULA)
6 Helpful Tutorials
12 Frequently Asked Questions**

**Assam-Calcu v3.1/ v3.0 is being hosted/ listed/ awarded by many software
archives on the web, including the coveted download.com:**

**Assam-Calcu: A Programmable All-Purpose
Calculator **

*Assam-Calcu* is a 12-digit
multi-purpose calculator that can store and recall millions of your old
calculations - whether ordinary or scientific. It may also be easily programmed
to run hundreds of calculation-steps in one go. It is designed to be equally
convenient for purposes as varied as the simplest grocery arithmetic as well as
the most advanced technological computations.

The basic operation in Assam-Calcu is execution of a simple command-line (say,
'Answer = 673+245'), of which the left side is a variable (say, 'Answer'), and
on the right side of which lies an expression (say '55*4' or 'Mass*(3.0E8)**2').
If the right side uses one or more variable(s), e.g., 'Mass', their values must
have been defined in earlier steps. Compared to most calculator-instruments, *Assam-Calcu*
offers the much wider range of 9.9E+300 to 1.0E-300 for its results. It also
contains a database of values for popular constants & conversion-factors.
Versions 3.x allow definition of several pre-defined SI-unit constants in one go.

This *Windows software*
(screenshot shown below) has been developed by Rituraj Kalita,
a resident of Guwahati, Assam (India) first during December, 2006 (using the *Visual
FoxPro 6* platform), and is being distributed as a freeware (i.e., free
software) by *Eastern
Star Software, Guwahati*.

Fig.: *Assam-Calcu* Screenshot

**Now, please do spare a few more minutes
to go through the following 'Tutorials' and 'Frequently Asked Questions'!
**

1. Personal Grocery Calculations in an
Indian Town:

Suppose someone in a small town in India has just bought from the local grocer's
some 5 kg of rice at Rs. (i.e., Indian Rupees) 15 per kg, 2 kg of potato at Rs.
8 per kg, 1.5 kg of lentil (masur dal) at Rs. 28 per kg, and half a kg of onion
at Rs. 15 per kg. To calculate this, proceed as follows: double-click at the *Assam-Calcu*
desktop-icon to run, then click at the Reset
Above Command button just ONCE to clear the right side of the command,
then type (on that right side) 5*15 + 2*8 + 1.5*28 + 0.5*15 (so as to represent
above calculation; you may also add there a subsequent comment, say: &&
rice, potato, lentil, onion respectively. Press Ctrl+End (or press Alt+R or
click at the Run Above Command or
Calculate it! button) to run this
command. The result (140.5) will be displayed, and the command with the result
will remain stored forever (may be recalled anytime later with just a
button-click at the Get Old Comm
button)!

2. Calculating the *Equated Monthly
Installment* (EMI) for an Indian bank loan:

The loans that the nationalized banks in
India provide to individuals for buying a car or building a house etc. are
generally to be repaid in equated monthly installments (EMIs). To calculate the *EMI*,
we first need to find what the loan amount (*AmLoan*) would have become
during the loan period, in absence of any payment. This is, clearly,

FinAmt = AmLoan*(Factor**NYears),
where Factor = 1 + PCRate/100, *PCRate*
(say, 12) being the percentage yearly rate of interest and *NYears* (say,
2.5) is the loan period in years. Using the value for *FinAmt*, the *EMI*
may be finally calculated by the relation (explanation omitted here):

EMI = Round(FinAmt*(Factor**(1/12) -
1)/(Factor**NYears - 1),0) where *Round(x,0)* function rounds off
the expression x to the nearest integer. Let us here think of a loan amount of
Rs. 60,000 to be paid in a period of 30 months (i.e., via 30 EMIs), where the
rate of interest is 12% per annum. Opening *Assam-Calcu*, we, so, run the
commands

AmLoan = 60000, NYears =
2.5 and PCRate = 12.
Then we calculate Factor =
1 + PCRate/100 and then

FinAmt = AmLoan*(Factor**NYears).
Then finally we calculate

EMI = Round(FinAmt*(Factor**(1/12)
- 1)/(Factor**NYears - 1),0), thereby arriving at the value 2308 (i.e.,
Rs. 2,308) for the EMI. Note: This calculation gives us only an approximate
value for the EMI. The exact bank rule for the calculation may somewhat differ,
leading to some variations for the EMI (an actual EMI at the *State Bank of
India*, for the aforesaid situation, was Rs. 2,347).

3. Calculation of the Translational
Partition Function of a Given Volume of a Particular Gas Kept at a Given
Temperature:

In chemistry, one needs to calculate the translational partition function (q_tr)
of a gas-system using relation: q_tr = (((2*pai*m0*k*T)**1.5)/(h**3))*V, where
pai is 3.1416, m0 is the mass of a gas molecule equaling Mm/Na (where Mm is the
molar mass and Na is the Avogadro number), k is the Boltzmann constant, T is the
Kelvin-scale temperature, h is the Planck constant and V is the volume of the
system. For oxygen gas (molar mass 0.032 kg/mol) enclosed in a container of
volume 0.005 cubic meter at 27 Centigrade temperature (i.e., at 300.15 Kelvin),
we may proceed as (knowing that Na is 6.022E+23, k is 1.381E-23 J/(K-mol) and
that h is 6.626E-34 J-s): (i) Click twice at 'Reset Above Command' button to
clear the old command (ii) Enter & Run the following commands one by one:
pai = 3.1416, Mm = 0.032, Na = 6.022E+23, m0 = Mm/Na, k = 1.381E-23, T = 300.15,
h = 6.626E-34, V = 0.005 and then finally q_tr = (((2*pai*m0*k*T)**1.5)/(h**3))*V
(iii) In that final step you've got the result 8.84909618558E+029, haven't you?

*Note:* (i) Most of the scientific calculators (i.e.,
the instrument, not a software) won't be able to directly find h**3, as it is
(in the popular SI unit) less than 1.0E-100. (ii) Performing this multi-step
calculation in such a simple non-programmable calculator instrument is as such
quite a cumbersome job (even if there arises no problem about the h**3
calculation)! (iii) To get the above steps in the form of a (FoxPro/
Visual-FoxPro) *program-listing*, re-run the above command steps again
using an *Assam-Calcu Re-Run *command, as explained in the 5th tutorial
below. (iv) The values of the above constants p, k,
R, N_{A}, T, h etc. (in SI unit) may also be *easily* brought onto
the command-line by clicking at the Constants
button, and then by clicking at the entry for the desired (pre-defined)
constant. This inbuilt
list of constants & conversion factors has been carefully collated (for
the physical-science constants are used the *2006 CODATA recommended values*)
with help from some standard resources, as detailed here.
(v) To find q_tr for nitrogen gas (Mm = 0.028) enclosed in 0.01 cubic meter
volume at 325 K temperature, may now just run (one by one) Mm = 0.028, m0 =
Mm/Na, T = 325, V = 0.01 and then q_tr = (((2*pai*m0*k*T)**1.5)/(h**3))*V (the
value thus obtained is 1.63214414284E+30, isn't it?)

4. Exact Calculation of the Constant in
the Wien's Displacement Law (in Physics) about Blackbody Radiation (Using an
Iterative Method):

While deriving the Wien's displacement law (regarding the wavelength for the
most intense radiation) from the Planck's law about blackbody radiation, it is
found that the Wien's constant b equals (hc/yk), where h is the Planck constant,
c is the speed of light in vacuum, k is the Boltzmann constant, and y is the
numerical solution of the transcendental equation y*exp(y)/(exp(y)-1) = 5, or in
other words, of the equation y = 5 - 5*exp(-y). The iterative method for
solution of this equation (in the last form) has a fast convergence, and so
starting with an approximate value of y (say, 5) we may continue iterations
using this relation y = 5 - 5*exp(-y). But at first, immediately after opening
Assam-Calcu, let us just click at the Define
Listed SI-Unit Constants button (or press Alt+D) to automatically define
the SI-unit values for a set of common constants including h, c and k. Now to
perform the iteration steps, we start by running the command y = 5 and then the
command y = 5 - 5*exp(-y). After this, we need to just press Ctrl+End again and
again to run this same command repeatedly. We see that just with 8 steps, the
value of y accurately converges to 4.96511423174, thus giving the value of the
constant b [employing an appropriate Assam-Calcu command b = h*c/(y*k)] as
0.00289776536 m K.

*Note: *Similarly, you may easily solve the equation y =
cos(y), starting with y = 0, reaching the solution y = 0.73908513322 in 74
steps -- yet within a duration of at most two minutes.

5. Using Gauss-Seidel Iteration Method
for Solution of a System of Linear Equations in Several Unknowns, via *Assam-Calcu*
'Re-Run' Command:

Let us now solve the set of three linear equations (x -2*y + 3*z = 10, x - 3*y +
2*z = 1, 3*x + y - z = 8) in the three unknowns (x, y, z) by using the
Gauss-Seidel iterative method. As per the well-known process of judging the
absolute values of the coefficients, we re-arrange the above set as: (3*x + y -
z = 8, x - 3*y + 2*z = 1, x - 2*y + 3*z = 10) and then proceed to iterate using
the following (equivalent) relations: x = (8 - y + z)/3, y = (-1 + 2*z + x)/3, z
= (10 - x + 2*y)/3

Let us initialize all the variables as 0, and then proceed with iterations. So
we first run the three commands x = 0, y = 0, z = 0. Then we run the three
commands x = (8 - y + z)/3, y = (-1 + 2*z + x)/3, z = (10 - x + 2*y)/3 one by
one.

* After this*, we go for the 'Re-Run Part of
Command-History' option (as we now have to just run the last three commands, in
a queue, again and again as per the prescription of the Gauss-Seidel iteration
method). So, now we click at the Re-Execute
a Defined Part of Command-History button (or press the equivalent hotkey
Alt+E). We now find that the 'Wizard for Generation of the Re-Run = Commands
Syntax' has appeared. With the help of this wizard, we choose the command x = (8
- y + z)/3 as the starting command, then choose the command (i.e., the next to
next command) z = (10 - x + 2*y)/3 as the ending command, and then choose a
halting time of 1 (one) second between successive commands. Now we click at Finish,
and find that a *Assam-Calcu* 'Re-Run' command of the form 'Re-Run =
Commands ranging from number 00000017 to number 00000019 (total 003 commands)
haltingly' has appeared. We now click at the 'Run Above Command' button, and
view the halting display of the three answers (for the first iteration). Again
we are to click at the same button to see another set, then again another, and
so on -- till the values of the unknowns x, y & z become practically
steady! We thus find that after 35 number of re-run operations we arrive at the
following final values for x, y & z:

x = 3.00000000000, y = 4.00000000000,
z = 5.00000000000, which comprise just the exact solution; while only after 11
re-run operations the results are quite close to the exact solution, i.e.,:

x = 3.00010986025, y = 3.99943728401, z =
4.99958823593.

Note: To jot
down on paper (or to copy into the clipboard) the aforesaid multiple-variable
values, it's advisable to click EITHER at the Show
Session Report button so as to open the *Session
Report* OR better at the List
Variables button to view just the *present
values* of the variables (i.e., of x, y & z).

6. Calculating (as per simple LCAO-MO
theory involving only an 1s-type AO-pair with a single orbital exponent variable
k) the *internuclear potential energy* U of hydrogen molecular ion (H_{2}^{+}
ion) as a function of its internuclear distance R:

As is nicely explained in Ch. 3 (Section: MO Theory of H_{2}^{+}
molecular ion) of *Quantum Chemistry* by Ira N. Levine (3rd Ed., Prentice Hall of India, New
Delhi, 2003), the internuclear potential energy U (which is
also the electronic energy including internuclear repulsion V_{NN}) of
the *ground* electronic state of H_{2}^{+} ion (as per the
aforesaid simple MO theory) is expressible by the following straightforward
relations:

Internuclear Potential Energy U =
(Haa + Hab)/(1 + Sab) + 1/R

*where*

Overlap integral Sab = (1 + k*R + k*k*R*R/3) *
exp((-1)*k*R)

Coulomb integral Haa = 0.5*k*k - k - 1/R + (k+1/R) *
exp((-2)*k*R)

Resonance Integral Hab = (-0.5)*k*k*Sab - k*(2-k)*(1+k*R)*exp((-1)*k*R)

[Here k is the optimum orbital exponent for a given distance R,
obtainable via variation theory using a computer-program such as the
one developed by this author and
freely available from his site (it is also included within the working
folder of Assam-Calcu). The program output displaying the (R, k)
values ranging from (0.4, 1.8327) to (8, 1.0000) in steps of 0.2 atomic unit
(a. u.) in R is as listed in the file INPE_Res.txt.]
It may be noted here that from the result of the above straightforward
calculation, pretty realistic values of the (equilibrium) bond-length R_{e}
and equilibrium bond-dissociation energy D_{e} for H_{2}^{+}
ion could be easily obtained.

To do this above calculation very quickly using Assam-Calcu,
first enter the commands R = 0.4 and k = 1.8327 therein. Then enter the above
three expressions for S_{ab}, H_{aa} and H_{ab} one by
one. Then enter the expression for U, getting hereby the value of U for R = 0.4.
Next, put R = 0.6 and the corresponding appropriate value for k (it is 1.7262)
into Assam-Calcu, and then just *re-run* the last four commands (the
appropriate *re-run command* may be generated by invoking the corresponding
*wizard*) for values
of S_{ab}, H_{aa}, H_{ab} and U. The new value of U for
R = 0.6 is thus obtained. Repeat the above process (the same *re-run command*
may be just recalled and used, there's no need to invoke the wizard again) for all other values of R
(up to 8.0) for which k is available in the aforesaid file-list.

Note: To
jot down current values of the variables (R, k, S_{ab},
H_{aa}, H_{ab},
U) better click at the List
Variables button.

*B. Frequently Asked Questions:*

01. I know that we may run *
Assam-Calcu* by double-clicking at the desktop icon named *'Assam-Calcu -
Prog-able All-P'*. But in my case, where is that *desktop icon*?

I'm sorry that in your case the *Assam-Calcu* Installer was unable to copy
the shortcut (link) icon (file) to your *Windows* desktop -- for most of the
computers it succeeds! But you may easily do that yourself. To do this yourself,
open the working folder (e.g., *C:\AssamCalcu*), starting from, say, *'My
Computer'*. From that working folder find and copy the link-file named *
'Assam-Calcu - Prog-able All-P' *(see picture of that link-file below), and then paste that
link-file to your *'Windows
desktop'* to facilitate running the *Assam-Calcu* application in future.

02. I keep getting an error message: *
'Row or column position is off the screen!'* whenever I try to run (i.e.,
open) *Assam-Calcu*. Where is the problem?

Most probably your monitor (VDU) screen resolution (*screen area* in *
Windows* terminology) is not set to a level high enough (i.e., at least to a
level of 800 by 600 pixels). You may try improving this particular *Windows*
setting (via *Control Panel - Display*), or as a simpler option may also
try changing the aforesaid desktop-icon's properties to have *Assam-Calcu*
always run in *'full-screen (i.e., maximized) window'* mode - this solution
also generally works.

03. Can't all such calculations be done via
writing some programs, say in FORTRAN or in BASIC?

Why not? But, is learning
full-fledged programming an easy job? *Assam-Calcu* resides in the
twilight zone, i.e., a no-man's-land, between Using a Calculator and
Doing Programming! So, it offers the benefits of programming even
to lay users with a very little knowledge of programming, and thus
slowly & unknowingly initiates people to the ideas and concepts
of computer-programming! [Also, besides, the less we talk about
the precision and the range of values for calculations in FORTRAN
or BASIC, the better it is!]

04. What? Can it also help us learn
computer-programming?

Surely. The more someone would use
*Assam-Calcu*, particularly via defining and manipulating
variables, the more would he or she feel at home with the basic ideas in
computer-programming. In fact, the 'Assam-Calcu
History Commands-Listing' obtainable from the Assam-Calcu 'History Re-Run'
command is itself almost a FORTRAN program!

05. May I add comments to a command so as
to annotate (mark) it?

Yes, surely. Just type an && sign
after the command, and type any comment portion beyond this
double-ampersand sign.

06. How to preserve a session report for
future reference?

The session report, ordinarily,
lasts only for the duration of the particular session. To
preserve it for future use, click at 'Session Report' to display the
same, then from File menu, click at 'Save As', then save this
report with a different name OR in a different folder. (Such a saved
report may be viewed with Notepad or with WordPad etc.)

07. Isn't there a difference between
integer and real variables, as in FORTRAN?

Thank God, there's none! (Have you
checked the tutorials?) In FORTRAN, if we write k =
1.381E-23, k will become simply zero. But NOT here. So, don't worry here
about this issue.

08. Should we write here 2 as 2.0, as in
old FORTRAN versions?

Not necessarily, again for the
same reason mentioned just above.

09. How to backup the command-history?

The command-history resides in the
file named *Comm_Hist* (exactly speaking, named *Comm_Hist.dbf*) in the working folder (generally,
the folder *C:\Assam_Calcu*).
So, to backup the command-history, just backup this particular file (say, to a
removable pen-drive). When your hard-disk fails, first re-install *Assam-Calcu*,
then copy this file back into the *Assam-Calcu *working folder.

Note: The similar *addition-history* of the inbuilt *Assam-Adder *resides
similarly in the file named *Addn_Hist* (exactly speaking, named *Addn_Hist.dbf*)
in the same working folder -- if this file exists, back up this too.

10. Why can't I change the *
Assam-Calcu* command-history? Can I renew (i.e., reset) it?

Why, history shouldn't be changed,
isn't it? But you may surely erase the entire command-history
at one go, if you really feel over-burdened with this heritage
of command-history! To do that, just delete the above-mentioned
file (*Comm_Hist.dbf*) - you'll see that
your command-history has been renewed, i.e., got reset.

11. Within the middle of a multi-step
calculation job, I unknowingly closed down *Assam-Calcu*! Without repeating
the earlier (i.e., already done) steps one by one, is there a faster way
through which I may recover the continuity of working on that multi-step job,
and then happily continue working on the remaining part of that calculation
project?

Yes, surely! In this situation, just generate (using the aforesaid *wizard*
for *Re-Run syntax generation*) the appropriate *re-run* command for
re-running the old commands of the lost last session in one go, and then just
run that *re-run command*. The automated re-running process would now take
only a few seconds. After that, you may happily continue working on the
remaining part of the long calculation project!

12. Why can't I exit from the calculator if
some report, data or help is being displayed?

Because someone may actually want
to only hide the display of that report etc., but may instead
unintentionally close the whole application! So, if you want to
exit from *Assam-Calcu*, first close any report (or data) window,
and then try to exit!

** Cite use of this package as:**

Assam-Calcu: A Programmable All-Purpose Calculator
3.1, © 2009 Rituraj Kalita, Guwahati (India).

**References:**

See the inbuilt list of constants & conversion factors.