Support: bob.hepple@gmail.com
Internet: https://gitlab.com/wef/gdcalc
Note: if you are using a locale other than English, please make sure you run gdcalc with the following command (thanks to Gösta):
LC_NUMERIC=en_US gdcalc &
Note: if you get a badly drawn border around windows in dcalc (curses-mode in a terminal) then try this:
TERM=gnome dcalc # or:
TERM=vte dcalc
It features:
Note that dCalc initially starts in algebraic mode - you can change to RPN mode in the Settings menu.
As well as the stack, which is always visible - a nice plus over an actual HP calculator - there are 10 integer and 10 real registers to store numbers.
All your numbers and settings are saved between sessions and dCalc works with other applications by supporting Cut and Paste into and out of the X register.
A full set of unit conversions including:
RPN is an easier way to use a calculator than the so-called algebraic method on so-called conventional calculators. It's just a shame that HP called it RPN, which means Reverse Polish Notation and that puts a lot of people off!
Think about how you do a sum on a piece of paper because that's how RPN works:
You write down the first number.
Then you write down the second number.
Then you do the sum.
Now, let's do it on dCalc. Type in the first number. You can use the BSP (backspace) key to correct any mistakes.
Now press the Enter key and the number jumps up into the Y register above X.
Now type the second number into the X register. When you've finished the second number press the key for the operation you want to do, for example, the + plus sign. There's your answer. Notice that the stack of registers drops down as numbers are used up - it's good old push and pop.
If you want to do another sum on the answer, just type in the new number and then the key for the operation, e.g. x, multiply.
You change the sign of your number with CHS
You can use BSP to backspace at any time
You can use CLX to completely clear X.
INV CLX clears the stack.
Invalid characters will be simply ignored e.g.
In Real modes:
L is simply the last X value - every time the number in X is used, it is stored into L. You can exchange X and L by simple clicking the L register..
The stack (Y, Z and T) is connected to X. Every time you click Enter, the numbers in X, Y, Z and T propagate upwards. The number in Z moves to T, Y moves to Z and X moves to Y. The number which was in T is forgotten.
Numbers move down the stack as they are consumed in X - e.g. if you click + repeatedly, Y and X are added and put into X, Z moves down to Y and T moves down to Z. Try it.
You'll notice that the number in T stays put - it is copied when the stack is consumed at the bottom - this is really useful in repeated calculations
e.g. to work out how interest compounds every month just put in the interest rate percent (as a real number - 1.1 means 10%) and then press Enter until the interest rate reaches the T register. Then type in your principal, say 1000.00 (don't press Enter!) Then just keep pressing the X (multiply) key - every time the principal is compounded by 10%.
There are other keys to manipulate the stack, mentioned elsewhere in this help. The stack is your best friend and using it well is the secret to effective calculation with RPN.
T->Z
Z->Y
Y->X and X goes back up to T.
The X key exchanges X and Y.
The registers are stored every time you exit so that the values are available next time.
You can add or subtract X to a register with ST+ and ST-
Ctl-c copies the X register into the clipboard which can then be used in a spreadsheet or Word processor. Similarly, if you are in another application and copy a number to the clipboard (with Ctl-x or Ctl-c) then you can paste it into X with Ctl-v.
Obviously, if it's not a number, you'll get an error message.
The first three operate on real (floating point) numbers and programming mode operates on integers. To change mode just use the buttons PRO FIN STA and SCI, the pull-down menus or the shortcut keys:
Ctl-s SCI scientific mode
Ctl-f FIN financial mode
Ctl-p PRO programming mode
Ctl-t STA statistics mode
Ascii format shows the value of each byte as a printable glyph (a-z, A-Z, 0-9 etc) or as an control/alt keystroke e.g. ^-a means control a (decimal 1), a-b means alt-b which is 0x80 + 0x62. Note that Ctl- shortcuts are not available in Asc mode - they enter the appropriate ascii code instead.
Hex numbers are displayed with a leading 0x, octals with a leading 0.
IP address numbers are displayed as 4 decimal numbers in the range 0-255, corresponding to bits 0-7, 8-15, 16-23 and 24-31. The same bit manipulations can be made with IP numbers as for any other format eg.to calculate a subnet address using AND. The other arithmetic operations operate as before but are fairly meaningless on an IP address.
There is an indicator to the left of the log key showing the current display number base.
The usual suspects including AND, OR, XOR, MOD, left/right shift, complement.
The PF key calculates the prime factors of X.
32 bit integers are used.
1 E 15 CHS
for 1.0E-15. Notice that before the E is entered, the CHS button applies to the sign of the number. After E is put in, CHS applies to the sign of the exponent.
Angles for trig functions are normally expressed in decimal degrees, but a minor mode exists for radians - use the keyboard shortcut or the pull down menu.
There is an indicator to the right of the message window showing degrees or radians setting.
There is also an invert function INV which reverses the sense of some functions - for example, if INV is clicked before SIN then the asin function is called instead. Hopefully this is intuitive.
There is an indicator to the right of the message window showing the status of Invert.
In all real modes you have access to:
Sci real mode displays as 1.0123E+01 with a mantissa and exponent.
Eng mode restricts the exponent to be a power of 3 e.g. 10.1230E0
h.ms converts a decimal hours into sexadecimal hours, minutes and seconds (or back if Invert is pressed first). e.g., 2.56 hours converts to 2 hours 33 minutes and 36 seconds which is displayed as 2.3336.
The r->p button converts from rectangular coordinates to polar (or the inverse)
The d->r button converts from degrees to radians (or the inverse).
In these calculations we are interested in:
With all the financial functions, the method of data entry is optimised - if you type in a number and then press a key (e.g. PMT) then dCalc stores that number. If you press a financial function without entering a number, dCalc calculates that value. If you press a financial key and the number is entered instead of calculated, just press the key again to perform the calculation.
Finally, if you press INV before a function, the current value is retrieved to X. You can see all the current values at once by pressing RCL (and then Cancel to return to the calculator)
The financial keys are:
There is a global setting under Menu->Settings which when set, allows a payment to be made at the start of the investment. Otherwise, the first payment is calculated at the end of the first period.
The DYS function allows you to calculate the number of days between 2 dates. The dates must be entered as YYYY.MMDD.
If prefixed by INV, DYS calculates the number of days in a nominal month as 30 days in a 360 day year.
The TDY key is a shortcut for today's date.
Type in:
3 Enter ×12 n ... 3 years is 36 months
1000 PV ... present value
5 Enter ÷12 i ... interest (5% per annum = 5/12 monthly)
0 PMT ... we are not making monthly payments
FV ... the final value is $1161.47 (shown as -1,161.47)
Another example: we have a $100,000 mortgage at 6% to be paid off completely after 20 years. What's the payment every month?
20 ×12 n ... 20 years
6 ÷12 i ... monthly interest
100000 PV ... present value
0 FV ... future value will be 0
PMT ... -716.43 per month.
Note the change of sign - the payment is a negative cash flow, and don't we know it!
The formula for these calculations is:
0=f+p(1+i)n + d((1+i)n - 1)(1+s.i) / i
where:
The m key gives the averages (means) of the X and Y values respectively.
StdD gives the standard deviation of both X and Y (into the X and Y registers). StdD, d is given by:
d² = (S(x²) - S(x)²/n)/(n-1)
where S(x) means the sum of x values
n displays the count.
Sum- subtracts the current X and Y from the total (e.g. if you entered a value incorrectly).
The statistics registers are:
yPx and yCx calculate permutations and combinations for x <= y. The integer part of x and y are used.
LR calculates a linear regression using the least squares method on the values input as (X, Y) pairs by Sum. A best fit straight line is presented as the slope m in the X register, and the Y intersect c in the Y register. The correlation coefficent r² is provided in Z - a value of r² closer to 1 means a good fit to a straight line. r² close to zero means a poor fit.
You can display the current linear regression formula with INV LR.
The best fit line is given by the formula
y = my + c
S(x) means the sum of x values:
Dx = n.S(x²) - (S(x))²
Dy = n.S(y²) - (S(y))²
m = (n.S(xy) - S(x).S(y))/Dx
c = (S(x²)S(y) - S(x)S(xy))/Dx
r² = m.Dx/Dy
f(X) calculates a value for Y from X using the straight line calculated by LR. Use the INV function to calculate the value for X for a given value of Y.
Some shortcuts are:
Ctl-c Copies X to the clipboard
Ctl-d sets Degree mode
Ctl-f Financial mode
Ctl-p Programming mode
Ctl-q Exits
Ctl-r Radians
Ctl-s Scientific mode
Ctl-t sTatistics mode
Ctl-v paste to X
* multiply
/ divide
+ plus
- minus
< shift X left by 1 bit (prog mode)
> shift X right by 1 bit (prog mode)
~ complement X (prog mode)
, (comma) CHS (real modes where decimal point = .)
% percent
GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
Preamble
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GNU GENERAL PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
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1. You may copy and distribute verbatim copies of the Program's
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the Program is not required to print an announcement.)
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the Program,
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In addition, mere aggregation of another work not based on the Program
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except as expressly provided under this License. Any attempt
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implemented by public license practices. Many people have made
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This section is intended to make thoroughly clear what is believed to
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may add an explicit geographical distribution limitation excluding
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NO WARRANTY
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FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
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END OF TERMS AND CONDITIONS
How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.
Copyright (C)
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
Also add information on how to contact you by electronic and paper mail.
If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) year name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License. Of course, the commands you use may
be called something other than `show w' and `show c'; they could even be
mouse-clicks or menu items--whatever suits your program.
You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the program, if
necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the program
`Gnomovision' (which makes passes at compilers) written by James Hacker.
, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your program into
proprietary programs. If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library. If this is what you want to do, use the GNU Library General
Public License instead of this License.