Chapter 2.4.3 Kcalc
===================

Kcalc is a scientific calculator application.

Features:

 - trignometric functions
 - factorials
 - built in mathematical and scientific constants.
 - memory
 - copy and paste

Useage
------
To do simple arithmetic click the numbers and then press the sign for addition, multiplication, subtraction,  or division. You can also type in the numbers and press + for addition, - for subtraction, * for multiplication and / for division. To view the answer press the button that is an =. 
 
.. image:: Kcalc.png

To make a number negative press the button that looks like a +/-. To insert decimals press the decimal point button which looks like . when you get to the part which is less than a whole number. To clear input from Kcalc Press the button with a C on it. To group operations so they happen together use the parenthesis to make things grouped to gether for example 2*(2+3) would give the result of 10 because it would add 2 and 3 and then multiply by two.

To copy and answer out of Kcalc press :kbd:`control + c` or :menuselection:`edit --> copy` from the menu. To paste a number into Kcalc you can press :kbd:`control + v` or :menuselection:`edit --> paste` from the menu. To cut the text from Kcalc press :kbd:`control +x` or :menuselection:`edit --> cut` from the menu.

Scientific calculator mode advanced fuctionality
------------------------------------------------

If you want even more functionality of Kcalc there is also scientific mode which is acessed from :menuselection:`settings --> scientific mode` radio button. The button 1/x takes takes 1 and divides it by the number currently on the calculator also known as taking the reciprocal. x! read x factorial will take the number X you entered and multiple each number going down to 1 for example 5! would multiply 5*4*3*2*1. 

The x squared button will take a x*x and multiply it by itself. The button with x and a superscript y will take x the number you have in will exponeniate x to the power of y. The x 10 with a supercript y will end up multiplying x by 10 to the power of y so for example to multiply 5 by 10 to the power of 3 entering in will give the answer of 5,000.

To change the unit that angles are measured in for triginometric units in Kcalc. Degrees take 360 to form a full circle while, 2Π radians form a full circle and 400 gradians form a full circle. The radio button for Deg is to select Degrees as the unit for angles, Rad selects radian as the unit of measurment of angles and Grad selects Gradians as the unit of measurement for angles. The Sin button takes what you have as the input and takes the trigonometric sine function of that value measured in the unit for angles you have selected. The cos button takes the cosine of the vlaue in the unit of angle you have selected. The tan button takes the tangent of the angle in the current units.  

.. image:: kcalc-scientific.png

Version
-------
Lubuntu ships with version 18.04.3 of Kcalc.

How to launch
-------------
To launch kcalc go to :menuselection:`accessories -> Kcalc` or run

.. code::

   kcalc 
 
from the command line. The icon for kcalc looks like a box with a + sign a - sign a multipliucation sign and an equals sign.
