This is an html version of the helpfile on the Psion - it might be useful on your PC.
Suite 296, 131 Old Cleveland Rd
Registration brings several benefits to you:
Firstly, registering will remove the nagging startup screen.
Secondly, you will be entitled to all future versions of dCalc for the Psion that I write and if you provide a email address you'll be notified when new versions are available.
Thirdly, by paying the (very small) registration fee, you will ensure that there will indeed be future versions of the program with morefunctions and fewer bugs.
It is a one-time registration valid for any Psion that you personally own. There is no crippled functionality in the unregistered program - just the nag screen and the nagging thought that you ought to do the right thing.
Corporate and other group terms are slightly different but are calculated at the same (already low!) rate as individual licences - one payment per Psion. As for personal use, it is a permanent license.
The precision in Scientific, Financial and Statistics mode is about 15 significant places of decimals.
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:
If you want to do know what a key will do, press the Explain button on the toolbar (or Ctl-X or Menu->Help->Explain key) and then the key. An explanation will be given instead of operating the key.
To exit this help, press Ctl-E. If you're desperate - drop me an email.
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. Write down the first number (by tapping the screen keys or pressing the number keys). You can use the BSP (backspace) key to correct any mistakes.
Now press the Enter key.
Now tap out the second number - the first number jumps up into the Y register above X - the large numeric display. When you've finished the second number press the key for the sum you want to do, for example, the + plus sign. There's your answer.
Not so very awful after all, reverse whatsit or not.
If you want to do another sum on the answer, just tap 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 (or the del key)
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 tapping the L register..
The stack (Y, Z and T) is connected to X. Every time you tap 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 tap + 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 tap 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.
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, subtract, multiply and divide X to a register with ST? which pops up a menu for:
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 Psion 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 32-bit integers. To change mode just use the buttons PRO FIN STA and SCI, the pull-down menus or shortcut keys:
Ctl-s SCI scientific mode
Ctl-f FIN financial mode
Ctl-p PRO programming mode
Ctl-t STA statistics mode
Don't confuse the SCI and the Sci buttons - the Sci button changes to Scientific Display mode (e.g. 1.0E-6 - see under Real Modes).
There is an indicator to the right of the message window showing the current 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 logarithm, pi, e, square root and 1/x keys do not work in Prog mode.
The P-F key calculates the prime factors of X.
32 bit integers are used.
Entering numbers should be fairly intuitive. For very large or small numbers, you can use exponent notation. For example, type:
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 toolbar Mode key 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 tapped 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 acces 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:
The CLf key clears all the finance registers which are:
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.
Compound Interest Example:
let's invest $1000 for 3 years at 5% per annum paid monthly.
3 Enter ×12 ... 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
FVl ... the final value is $1161.47
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 Enter ×12 n ... 20 years
6 Enter ÷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
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 OPL formula given can be copied and pasted into one of the programmable keys or into the graphs function.
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.
OPL is similar to Basic and gives you access to a huge number of functions and all the data stored in the calculator. A full tutorial on OPL is not possible here (see the Symbian website) but here is a short guide to get started.
You can access the stack variables - X Y Z T L and the registers R0..R10. The integer variables (from PROG mode) are also available as X& Y& Z& T& L& R0&..R10& but due to limitations in the EVAL function of OPL, the programmable keys are only available in floating point modes SCi, FIN and STATs.
The arithmetic operations are:
+ - * / (note: not × and ÷)
** for exponentiation (not ^)
SQR(x) for square root
% for percentage
Functions: Note that built-in OPL functions are notated in capitals here e.g. SIN(x). dcalc internal functions are denoted in lower case and have a colon.
SIN(x), ASIN(x), COS(x), ACOS(x), TAN(x), ATAN(x), atan2:(y,x)
sinh:(x), asinh:(x), cosh:(x), acosh:(x), tanh:(x), atanh:(x)
RAD(x) converts from degrees to radians - the trig functions all use radians so you need to do SIN(RAD(x)) if x is in degrees.
EXP(x), LOG(x) (base 10), LN(x) (base e)
ABS(x) gives the absolute value of x.
INTf(X) gives the integer part of x.
Extra functions available:
RND gives a random number from 0 to 1.
seed:(x) sets the random number seed to x. dcalc sets the seed on startup with the time of day in millisecs.
fact:(x,y) gives N!/M! e.g. fact:(4,1) gives 4!
f(xn+1) = xn - f(xn)/f'(xn)
f'(X) is the derivative of f(X) (or dy/dx). Both functions must operate on X for this to work.
dcalc will stop iterating after 30 seconds if a solution is not converging. Of course both functions f(X) and f'(X) must be entered correctly before the iteration can proceed - check them out individually. They work just like the other programmable keys on X.
For example, we want to find values of x that solve the equation:
x3 + 9x2 + 11x - 21 = 0
Put the following OPL into the f(X) and f'(X) programmable function keys:
f(X): x*x*x + 9*x*x + 11*x - 21
f'(X): 3*x*x + 18*x + 11
Now put a guess into the X register - e.g. 20 and press the N-R button and you should get the answer 1. Since this is a tertiary equation you can find up to 3 solutions - you'll need to try other starting guesses to find the other solutions - or factor out the first solution and solve the simpler quadratic:
x3 + 9x2 + 11x - 21 =
(x - 1)(x2 + 10x + 21)
To enter the graphics menu, select
Menu->Tools->Graphics or use the Graphs button on the toolbar.
Creating a graph consists of
To finish viewing the plot, press the Calc button to return to the dCalc menu.
While the plot is displayed, you can touch the screen and a cursor and coordinate readout will appear. This can be useful, for example, to get the coordinates of an intersection of two graphs
The plot can be controlled through the Globals, Axes, Ticks and Functions settings on the graphics menu.
With Global you can set up the size of the plot e.g. if you want it smaller than the default full screen. Smaller plots are faster.
The Plot Interval governs the distance in X between consecutive plot points - the higher the Plot Interval, the coarser and faster the plot. Finally, a Grid can be selected - either dots or faint lines.
Under the Graph Axes element of the graphics menu, you can set the X axis... i.e. the value in Y that the X axis is to be drawn - in units of Y, of course. The default is 0. Similarly, set the Y axis as the value in X that the Y axis is to be drawn. You can also set the range in X and Y that you want plotted.
The Graph Ticks item allows you to set the interval for axis ticks (on grid dots if selected under Globals). Similarly, the interval for axis labels can be set - don't set them too close or you'll get a blur.
The Functions menu allows you to specify the OPL code that you want plotted. There is a discussion of OPL under the Programmable Keys heading which applies equally to this section. There is a Pen Width item for each function - a width of 0 supresses the plot of the corresponding function. Larger pen numbers give thicker plots. The graphing functions are stored independent of the Programmable Keys f1-f5 - but you can always use copy and paste between them.
All plot settings are saved by dcalc on exit along with all other settings in the dcalc.ini file.
The format of the plot file is that provided by the standard Psion gSAVEBIT OPL call - in other words, an MBM file. Curiously, the standard Psion Sketch application does not read this format by default but you can persuade it to import it. You have to open Sketch, clear the screen (Menu->Edit->Delete all or Ctl-d), and then merge in the plot file (Menu->File->More->Merge in) making sure you set the File Type to EPOC Picture.
You can also, read the graph format into a PC and convert it to other formats including Sketch. Or you can get the excellent mbmview program to convert it on the Psion.
The conversions are arranged in groups:
You can change the rates and the names of the currencies by tapping on Modify Rates while in the currency converter. Your settings will be saved.
Whenever any rate is changed, the date displayed on the converter is changed to the current date.
There is a daily currency file available at http://www.geocities.com/bob_hepple/dcalc/psion/update.txt
Download it to the Psion and use Menu->File->Read currencies or Ctl-y to read it into dCalc. Newer values will be updated but other currencies manually entered will not be affected.
More detail on currencies.
The currency rates are read and stored by dCalc whenever the program is started or exited. There is a plain text file: C:\System\Apps\Dcalc\Currency.txt with the following format:
08 Feb 201
The first line is the date that the rates apply. Up to 12 characters are used. The remaining lines consist of a currency abbreviation (up to 12 characters) a comma and the rate. The rate may be an OPL expression such as 1/1.234.
You can edit this file as you wish - just make sure it is formatted correctly and is saved as a text file.
Some shortcuts are:
Ctl-a displays the 'About' message
Ctl-A Axes in graphics mode
Ctl-c Copies X to the clipboard
Ctl-C conversion in real modes
Ctl-d sets Degree mode
Ctl-f Financial mode
Ctl-F Functions in graphics mode
Ctl-g Graphics on/off
Ctl-G Globals in graphics mode
Ctl-h Toggle payment at N=0
Ctl-i set number of decImal places
Ctl-o set preferences
Ctl-p Programming mode
Ctl-s Scientific mode
Ctl-t sTatistics mode
Ctl-v paste to X
Ctl-X Explain next key
Ctl-y Read in currency file
x swap X and Y
y h multiply (j on AZERTY kb)
u j divide (k on AZERTY kb)
i k plus (l on AZERTY kb)
o l minus (m on AZERTY kb)
< shift X left by 1 bit (prog mode)
> shift Y right by 1 bit (prog mode)
~ complement X (prog mode)
& toggle FIX & SCI display (real modes)
\ 1/X (reciprocal) (real modes)
, (comma) CHS (real modes where decimal point = .)
. (full stop) CHS (real modes where decimal point =,)
In addition, once DCALC is running, you can bring it to the front with the hotkey, which is initially set to Ctl-Fn-D. You can change that to any other key through Menu->Tools->Hotkey or Ctl-o.
Instead of using a Ctl-Fn- keystroke you can let dcalc steal the Calc button (below the screen) from the built-in calculator (not on the Netbook).
You can set the keyboard type to one of:
English/Euro ... ×=y/h ÷=u/j +=i/k -=o/l
MC218 ... ×=r ÷=t +=y -=u
French/AZERTY ... ×=j ÷=k += l -=m
Thanks to Richard Smedley for SafeOPL and ScrambleOPL copy protection software: http://www.cix.co.uk/~rsmedley/s5/
Thanks to Manfred Schories for the German translation.
email address:: firstname.lastname@example.org
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