A calculator, of course. But more specifically, a calculator that can handle integers, rational numbers, and matrices. The program is designed to maintain maximum precision throughout calculations, and to make it easy to keep track of several values at once.
When running the program, simply enter the values you want to operate on, then the operation you want to perform. The way this calculator operates, it lends itself to Reverse Polish Notation. Instead of writing
2 + 3
We instead write
2 3 +
This makes it easy to specify many operations and operands without getting bogged down in parentheses. YOU specify the order in which operations are performed, so there is no ambiguity. To compute
(2 + 3 * 4) / (7 + 11 / 2)
We instead write
2 3 4 * + 7 11 2 / + /
You can also write them one operation at a time: each time you press enter, the program will show you which values it has stored. This calculator also supports more complex operations, including the use of matrices and stack operations. To learn the available tools in more detail, read the sections below.
Assuming you have the executable in the directory, simply run with
./calc
When the program begins, you are placed in the main screen. From here, the program will begin accepting input. There are two kinds of input:
- Literals, which come in the form of numbers
- Commands, which are always a single non-numeric character.
The literals accepted in the calculator program are:
- Integers, simply a sequence of numeric characters
- Floating-point numbers, a sequence of numbers with a single decimal somewhere
- Fractions, two integers (a numerator and denominator), separated by a slash ('/') with no space between the slash and the integers
If you type a literal while in the main screen, it will place the associated value onto the stack, which contains the list of values that the program is keeping track of. The contents of the stack are printed out any time you press enter while on the main screen.
The commands accepted while on the main screen fall into three main categories:
- Arithmetic commands, which perform arithmetic operations on values in the stack
- Stack commands, which manipulate the contents of the stack
- Screen commands, which change the current screen of the program
Note that commands and literals can be written in a single phrase, leading to a compact representation. For example, the sequence
2c 5 +
represents four commands: "Add 2 to the stack", "Change the sign of 2", "Add 5 to the stack", "Add the two values on the stack". After this command, the stack will contain the single value 3.
The arithmetic commands perform an operation on one or more values in the stack, and replace them with the result of the computation. The operations are performed always on the top (most recently entered) values of the stack; the result becomes the new top of the stack. The available arithmetic commands are:
-
+: Adds the top two values on the stack
2 3 +results in 5
-
-: Subtracts the top value on the stack from the value beneath it
2 3 -results in -1
-
*: Multiplies the top two values on the stack
2 3 *results in 6
-
/: Divides the second value on the stack by the top value
2 3 /results in 2/3 or 0.6666
-
^: Raises the second value on the stack to an exponent specified by the top value
2 3 ^results in 8
-
!: Takes the factorial of the top value on the stack
4!results in 24
-
c: Changes the sign of the top value on the stack
4cresults in -4
-
r: Takes the square root of the top value on the stack
4rresults in 2
The stack commands change the values on the stack. The available stack commands are:
- d: Creates a duplicate of the top value on the stack
- p: "Pops", or removes, the top value on the stack
- s: Swaps the top two values on the stack
- z: "Zeroes", or empties, the stack
The screen commands switch to one of the other screens, where different and more specialized commands are available. The available screen commands are:
- h: Opens the help screen, from which you can access information about the program
- o: Opens the options screen, from which you can set certain aspects of the program
- m: Opens the matrix screen, from which you can create or manipulate matrices
- q: Quit the program
The stack can contain matrices, which respond to the same stack commands as numbers, and to the arithmetic operations that are defined on matrices (Addition and subtraction with same-sized matrices, multiplication with numbers or correctly-sized matrices, sign change, and power with numbers). From the matrix screen, you can create a matrix, or you can manipulate the matrix on top of the stack (if there is one) with matrix-specific operations. Available creation commands are:
- i: Creates an identity matrix of a particular size. After running this command, you will be asked for the number of rows and columns.
- n: Creates a new matrix. After running this command, you will be asked for the number of rows and columns in the matrix, and then for the values of the matrix, line-by-line.
Available matrix-specific operations are:
- a: Add a multiple of one row to another. You will be asked which row to add to, which row to add, and by what factor.
- e: Reduce the matrix to row-echelon form.
- m: Multiply a row by a certain factor.
- s: Swap two rows. You will be asked for the numbers of the rows to swap.