App Review: Programmable Calculator (Jeff Glenn)
Programmable Calculator app screen shots 
Author: Jeff Glenn
Date: 2014
Cost: 99 cents
Version
Reviewed: 1.2.0, 3/20/2015
Type:
Programmable, Basic
Platform: Android
Mathematical Programming From Scratch
The
Programmable Calculator app lives up to its name. It gives you barebones as far as features are
concerned: just the four arithmetic functions (addition, subtraction,
multiplication, and division) and nothing else.
Not even square root or π.
Their website, http://igram.org/progcalc/user_manual.html,
has a program to calculate square roots.
Before there
were scientific calculators and scientific functions arrived on our computers,
they had to all be programmed using just arithmetic functions.
If you want to
try scientific programming on this app, you may want to consult the 1975 book Scientific
Analysis on the Pocket Calculator by Jon M. Smith (John Wiley & Sons),
or this website by Ted Muller: http://tedmuller.us/Math/Calculator1'Introduction.htm
Needless to the
say, the Programmable Calculator operates on Chain logic. That is, it doesn’t follow the algebraic
order of operations ( 2, [ + ], 3, [ *
], 4, [ = ] returns 20 instead of 14).
Press [ f ],
[R/S] to access the options and user manual. Options include turning sound and
vibration on for key presses, which I highly recommend.
Programming
The programming
features on this app are laid directly on the keyboard. There are 10 memory registers (R0 through
R9), 10 labels (again, 0 – 9), and the accumulator (number on the display) to
use. Programs can be saved and loaded
with file names. The limit seems to be
the amount of memory on your Android device (phone).
What is weird
is that certain commands, such as the comparison, store, and recall, will prompt
you for either the accumulator (display, by pressing the [ . ]), a specific
memory register (0 – 9), or a constant, which will require a press of the
equals key [ = ] first. This takes
getting used to.
Here are some
commands.
[ IN ]. Input.
(in). Stores the prompted value
to a designated memory register. This
command also acts as a prompt. If a
print string proceeds the input command, the prompt gets attached to the end of
the screen.
[ OUT ]. Output.
(out) Displays the contents of a
designated memory register. Execution
doesn’t stop on output, so if this command is the last command before eof (end
of file), you’ll need either an R/S (run/stop) or sleep. If a print string proceeds the output
command, the value gets attached to the end of the print string.
[ PRT ]. Print
(prt). Prints a string. Without a string, this command would clear
the display instead.
[ LBL] and [
GTO ]. Label (lbl) and go to (gto), respectively.
[ DSZ ]. Decrement and skip. (dsz)
Designates a register to decrease by 1.
If the result is zero, the next command is stepped.
[ < ], [ =
], [ > ], ≤, ≠, ≥. Comparisons. Compares the accumulator (display) to a designated
register. If the test is true, the next
command is executed. Otherwise, the next
command is skipped. Code names: lt, eq, gt, le, ne, and ge respectively.
[ SET ]. Sets the accumulator (display) to a
designated value.
[ CLR ]. Clears the accumulator (display).
[ STO ] and [
RCL ]. Store and recall.
The arithmetic
keys: [ + ], [  ], [ * ], [ ÷ ]. These
keys work quite differently in program mode.
You are prompted to designate a register for the operation to work on
(like recall arithmetic). You can also
choose the accumulator by pressing [ . ].
Pressing the equals key [ = ] allows for a numeric constant to be
entered. All numeric constants are shown
as floating point numbers. For example, add 1.0
would add 1, but add 1 would add the value of register 1. Code names are add, sub, mul, and div,
respectively.
[SLEEP] This command pauses execution. A value of 1,000 amounts to 1 second. 2,000
for 2 seconds, etc. Code name: slp. This
works similarly to the comparison and arithmetic commands.
[R/S] Run/Stop.
Code name: stp.
[REM] Remark, comment.
If I understand
[TIME] correctly, this records the time value onto the calculator app. I haven’t tried this yet.
Sample Programs
I suggest
trying the sample programs listed below or listed online manual ( http://igram.org/progcalc/user_manual.html
) before programing on your own. I really got stuck with the input instruction
and how to get the R/S key to work out.
Square Plus 1
This program
calculates the function f(x) = x^2 + 1
Step

Line

Comment

00

prt “Number: “

Prompt

01

in 0

Input to R0

02

prt (blank string)

Keys: [PRT],
[DONE]
Clears the
display

03

rcl 0


04

mul 0

R0 * R0

05

add 1.0

Keys: [ + ],
[ = ], 1, [ = ]

06

sto 1

Store result
in R1

07

out 1

Display R1

08

sleep 1000.0

Keys: [ f ], [OUT] (SLEEP), [ = ], 1000, [ = ]

09

eof

End of
Program

Example:
Input: 6, Result: 37
Input: 11,
Result: 122
Area of a Circle
The value of π must
be manually entered. I use 10 digits.
Step

Line

Comment

00

rem “Area:
Circle”

Remark

01

prt ([DONE])

Clear the
display

02

prt “Radius:
“

Prompt: “Radius”

03

in 0

Input to R0

04

prt


05

rcl 0


06

mul 0

R0 * R0

07

mul (=)
3.1415926535

Use [ = ] to
enter the constant π

08

sto 1

Store result
in R1

09

out 1

Display R1

10

eof

End of
Program

Example:
Input: 2.5, Result:
19.634954084375
Power: x^y
Conditions: x > 0, y is an integer. Neither condition is tested. Since only arithmetic functions are available,
a loop is used.
Step

Line

Comment

00

prt

Clear the
display

01

prt “x = “

Prompt for x

02

in 0

Input R0

03

rcl 0


04

sto 2

Store R0 in
R2 (copy x)

05

prt


06

prt “y
(integer) = “

Prompt for y,
with reminder

07

in 1

Input R1

08

lbl 0

Label 0,
begin the loop

09

rcl 0


10

mul 2


11

sto 0

R0 * R2 → R0

12

rcl 1


13

sub 1.0

Keys: [  ],
[ = ], 1, [ = ]
R1 – 1

14

sto 1

R1 – 1 → R1

15

rcl 1

Put R1 in the
display (accumulator)

16

gt 1.0

Keys: [ >
], [ = ], 1, [ = ]
Is R1 > 1?

17

gto 0

Goto Label 0
if R1 > 1

18

prt


19

prt “x^y = “

Start result string

20

out 0

Attach R0
(result) to string

21

eof


Examples:
Input: x = 3, y = 5.
Result: 243
Input: x = 2.7, y = 8. Result: 2824.2953648100015
Modulus
This program
calculates x mod y, where x and y are both positive and x > y.
Step

Line

Comment

00

prt

Clear the
display

01

prt “x
(>0) = “

Prompt for x

02

in 0

Input R0

03

prt


04

prt “y
(>0) = “

Prompt for y

05

in 1

Input R1

06

lbl 0

Label 0,
begin the loop

07

rcl 0


08

sub 1

Subtract R1

09

sto 0

R0 – R1 → R0

10

rcl 0


11

sub 1


12

ge 0.0

Keys: [ ≥ ],
[ = ], 0 , [ = ]
R0 – R1 ≥ 0?

13

gto 0

Goto label 0,
repeat loop if R0 ≥ R1

14

prt


15

prt “x mod y
= “

Begin result
string

16

out 0

Attach R0 to
the result string

17

eof


Examples:
Input: x = 44, y = 3. Result:
44 mod 3 = 2
Input: x = 76, y = 20. Result:
76 mod 20 = 6
Final Verdict
The programming
language seems to be clumsy at first and it will take some getting used
to. Turning on the sound and vibration
made operating the app much better because the touch has to be precise. I can see how this app can easily frustrate
people.
Also it is very
unusual that the equals key is at the top row of the keyboard instead of the
usual location at the bottom.
With a lack of
scientific functions, I recommend this app if:
(1) You want to
engage mathematical programming from scratch.
Remember that all the scientific,
financial, and advanced features had to be originally programmed using the four
arithmetic functions themselves!
(2) You want a challenge.
Eddie
This blog is
property of Edward Shore, 2017.