SDP is a software intended for the use of scientists and engineers and students of courses in science (and engineering ) it can calculate almost any calculation needed (by those people) including units complex numbers and all sorts of functions and brackets you might need.
It features (among others)

a. Easy complex number manipulation.
b. An integrated unit converter (i.e. you type the units into the question as written on paper).
c.  An error calculator (integrated, built in) -> you get the accuracy of your result
based on the accuracy of your parameters.
d.  Easy access to physical constants . (click of a button)
e.  Graphical user interface (no strange commands to remember)
f.  No polish notation , natural use.
g. Flexible interface - you can change the buttons on the screen.
h. Ability to add infinite number of units in infinite number of categories.
i.  Ability to add as many new functions as you need. (and more).
j.  Cut and paste results and questions to/from other programs (say your word
processor or spreadsheet).
k.  A small spreadsheet to make repeating calculations easy.
l.  The same utility is available for unix too (I hope mac will be available soon).
m.  You can choose your user interface to match you needs.
n. Plot your results and any function you want to a graph.
o. See the accuracy of your result on the graph.
p. Do numerical integration , minimization maximization and solve equations.
q. Show the results on a graph.
r. Find a best matching function to it.
s. Plot functions to see what they look like.
t. Use random numbers with any distribution you like.
 
 

2. How to install:
   Just run setup.exe

3. How to uninstall
   Run uninst.bat.

The best advice on using SDP is this.

This software understands questions written in a very similar way to the way most people write it on paper. So just type it in the question entry and press enter.
However SDP separates the word using spaces and other characters (as , and ()) so if you are not sure if a space is in order put one, because if you type sin30 SDP will try to look for a function named sin30.(if you use the screen buttons , spaces are being put in place automatically so use it!).

And now lets dive into the mud!.
(to make things easy you can copy -> paste from here (or any other document) to SDP).
 
a. start SDP - the basic unit will appear on the screen.(double click on SDP.exe, you can drag it to your start button to make it easier to use).

b. open SDP Control from the options menu , a control window will appear
    it has some parts
        i. basic numbers and 4 basic functions (if you need help you don't need this program) and i (sqrt of -1) ,and ± button to specify the accuracy of your numbers , you can type any number using those buttons .
        ii. basic units (Meter Kg Second °k Coulomb(charge) and Mol(number of molecules)
        iii. To the right you have some physical constants , you can see a short description of at the button (yellow bar, keep looking at this yellow bar at the bottom.)
        iv. Below you can find some basic functions (watch the yellow bar)
        v.  On the left you can see 4 memory cells each has an in and out button.

Now lets type some in question :

1 Mol R* 25 °c

          (to get the ° mark press the green button or type in D)

you can see the question typed into the green question bar on the basic window

Thease are buttons the file menu you can press the:
    a. Calculate MKS button (result in meter kg second SI system)
    b. Calculate CGS button (results in centimeters gram second)
    c. just type Enter at the green bar where the question was typed.(use the last unit system you have used)
          ( in fact you could have typed the whole question there yourself.)
    d. press the "=" button and use the last unit system you have used.

So press Calculate MKS (or MKS on the main window file menu)
The answer bar shows the result in MKS as
 
2479.0278 {M^(2)}{Kg^(1)}{Sec^(-2)}     (i.e. energy units)

Now open the Units window (on the menu driven version it is in the options menu) . you see a new window pop up where you can find more units you might need (press more and more units will appear) , you Could have used all those units (and more) in you calculation .
Now back to the calculation. You know (if you don't read on SDP knows) the result is in energy units and you want in to be shown as calories just press convert to (on the units window) press the calorie(unit window or unit browser) button and press the calculate button which popped up.
The result window has now changed to 593.068853 Cal (the answer you wanted).
 

Now suppose you need it in unit not shown on those options say Hartree (some atomic unit).
press the lower right button on the main window (it says "->") (this in only if you have a fast computer because this takes some time) press it ones the bottom button will say Joul , twice it will say Joule another time and it is erg and the fourth time it will say Hartree (all those units are energy units as you wanted) press the bottom button (which now says Hartree) and the result window is changed to 5.68689097e+20 Hartree .

Now suppose you wanted to use Hartree in a calculation how do you enter it inside , well the first way is to just enter it in the question window (using the keyboard) but remember SDP separates upper case from lower case.
The second is to use the second units browser (above the one you have used already) we have not used yet press the second -> button on the basic window and the unit Kg will appear (with it's value) on the browser button press it and the word Kg is inserted, you can look up units this way , the units are in the same order they are in the .un file (mks.un cgs.un or other). Edit it so units you use more frequently will appear first.

The third way is to open the Definitions window in the options window ,a new window will appear type Hartree on one of the green bars and now the button next to it will act as an Hartree button (you can also use it as function button or put constant there.)
 
By opening the prefixes window you will get some SI standard prefixes you can use on any unit.
Now lets do another calculation
lets do

exp((5+4*i)*tan(55 °))

To do a new calculation press one of the many clear buttons.
Type the question any way you want (keyboard or screen buttons , if you are using the keyboard use capital D instead of the ° symbol)

Press calculate MKS and the result is 1262.366223*exp(i*-0.57059328)
That might look like a new question but it is very useful in physics .However if you want it in the regular way press "a+I*b" on the main window and you'll get 1062.37966+i*-681.841527 you can also change the way the result is shown using the fix/norm/sci buttons on the main window and the precision buttons on the SDP Control button.

Now about error calculation.
Not always you get accurate measurements , and than after a long calculation you need to know how accurate is your result. SDP does that for you , you simply type your parameters inside brackets with the ± (or err if you use the keyboard) sign before the error approximate size. and you will get the result with it's accuracy.
How does SDP calculate that ?
SDP multiplies the derivative of the function by the error of the variable to get a 1st order approximation of the error possible (common practice in physics).
(using the first order of Taylor's series).

example :

calculate the speed of a turtle

(5 Meter ±( 2 Cm))/(6 Hour ± (2 Minute))
=(0.00023148148 ±2.2119342E-6) {Mps} =(0.00083333333±7.9629629e-06) {Kmph } (kilometer per hour)

More buttons you may want to use are :
Copy and Paste copies and pastes to the clipboard (and other programs).
Res gives you the last result .
Undo restores the last calculation
Define lets you easily define new units  you might need
In the red buttons you can type a name of another units file you want to use (press enter and get the result)
Controls opens all the window and Hide controls closes all the windows

Using the mini spreadsheet.
 a. Press the sheet button (top/Basic window) (or options menu)
 b. In the new window , type questions in the green entries and get the result in the blue ones.
 c. If you need to refer to the result of the question marked as 2 write #2 in your question.
 d. Each type you press enter only one calculation is made. if you want the whole page recalculated press ReCalculate.

you can use all the other SDP functions in this sheet.

5. Other things about units:

    If you typed the question 2 M ^ 2 you would have got 4 {Meter^(2)} that is fine if you wanted to know the area of a 2M by 2M square However if you wanted to put in 2 square meters you should have typed 2 {M^2} the {} are saying this is a unit , it is always a good practice to use it . you can have any unit to any power inside even {Coulomb Joule Second Inch} unlike other unit converters which will not accept this.
You can find the { } buttons on the keyboard and on the units window.

6. How to add units and functions (Registered users only)

SO EASY!
 Adding a new unit.
   a. Make sure you are using the unit system you want to add the unit to
                    (MKS/CGS or others)
   b. Press the define on the main screen.(options menu on menu UI)
   c. Fill in the bars at the top side of the wizard (look at the example on the right
           side)
   d. Press add.(upper one).
Adding a new function
   a. Make sure you use the right formula file (usually "general" will do).
   b. Press the define button.
   c. Fill in the details (say myfunc on the first bar , and hisfunc(2*%0) on the second).
  d. remember the first variable the function accepts is %0 the second is %1 etc...
  e. press the Add button on the bottom.

To register you have to send 30 US$ to (private usage) or 100 US$ (Not private users) to:

Ortal Alpert ,
2 Giva't beit hakerem St.,
Jerusalem
Israel
96268

And your email address and name. (And money off course).

8. Where do I get support

Registered user get support by email to ortal@batata.fh.huji.ac.il
 
 

9. bug fixes
 bug fixes -Registered users are notified by email others must download the latest version from http://www.uc.8m.com
 

10. Warranty of SDP

None. For 30$ I cannot be responsible for the results you get.
But I use it myself.
 

11. Want anything else in SDP
Every software has bugs , look at bill's software ,However unlike bill I am trying to fix it, so if you think you have found one :

 Just email me (no response promised) thanks.
    ortal@batata.fh.huji.ac.il

12. Want to have SDP on your site
 
Just email me and have a copy I just want to know.
 
 
 

One other thing about units .
if you define a unit file that might be useful to others you might want to mail it to me. and if you need a totally different set of units just use mks and mks.un as a template and than type the name of your new unit file in the red button on the main screen.
you can also make several formula files just type a new name in the SDP Control and add functions as described above. than you can switch between the files by entering a different value in SDP Control.
 
 

How to enter a question:
You can either use the keyboard after clicking the green entry in the main window or use the screen buttons on the windows.
and you can also copy a question fro another utility using the pase mechanism.

and than press enter to get the result.

How to change the unit set you use
On a menu driven SDP use open new unit file in the file menu or calculate mks/cgs in the same menu.
On a button driven SDP use calculate MKS/CGS or enter a new unit file in the red button and press enter.

How to convert the result