Octave Programming: Glossary

Key Points

Analyzing Patient Data
  • Octave stores data in arrays.

  • Use csvread to read tabular CSV data into a program.

  • Use plot to visualize data.

Writing Octave Scripts (m-files)
  • Save Octave code in files with a .m suffix.

Repeating With Loops
  • Use for to create a loop that repeats one or more operations.

Making Choices
  • Use if and else to make choices based on values in your program.

Creating Functions
  • Break programs up into short, single-purpose functions with meaningful names.

  • Define functions using the function keyword.

Defensive Programming
  • Use assertions to catch errors, and to document what behavior is expected.

  • Initialize variables with actual values rather than arbitrary constants.

  • Write tests before code.


additive color model
A way to represent colors as the sum of contributions from primary colors such as red, green, and blue.
A value given to a function or program when it runs. The term is often used interchangeably (and inconsistently) with parameter.
An expression which is supposed to be true at a particular point in a program. Programmers typically put assertions in their code to check for errors; if the assertion fails (i.e., if the expression evaluates as false), the program halts and produces an error message. See also: invariant, precondition, postcondition.
To give a value a name by associating a variable with it.
(of a function): the statements that are executed when a function runs.
call stack
A data structure inside a running program that keeps track of active function calls.
Treating text as if upper and lower case characters of the same letter were the same. See also: case-sensitive.
Treating text as if upper and lower case characters of the same letter are different. See also: case-insensitive.
A remark in a program that is intended to help human readers understand what is going on, but is ignored by the computer. Comments in MATLAB start with a % character and run to the end of the line;
To apply one function to the result of another, such as f(g(x)).
conditional statement
A statement in a program that might or might not be executed depending on whether a test is true or false.
comma-separated values
(CSV) A common textual representation for tables in which the values in each row are separated by commas.
default value
A value to use for a parameter if nothing is specified explicitly.
defensive programming
The practice of writing programs that check their own operation to catch errors as early as possible.
A character or characters used to separate individual values, such as the commas between columns in a CSV file.
Human-language text written to explain what software does, how it works, or how to use it.
empty string
A character string containing no characters, often thought of as the “zero” of text.
The practice of hiding something’s implementation details so that the rest of a program can worry about what it does rather than how it does it.
floating-point number
A number containing a fractional part and an exponent. See also: integer.
for loop
A loop that is executed once for each value in some kind of set, list, or range. See also: while loop.
function call
A use of a function in another piece of software.
in-place operators
An operator such as += that provides a shorthand notation for the common case in which the variable being assigned to is also an operand on the right hand side of the assignment. For example, the statement x += 3 means the same thing as x = x + 3.
A subscript that specifies the location of a single value in a collection, such as a single pixel in an image.
inner loop
A loop that is inside another loop. See also: outer loop.
A whole number, such as -12343. See also: floating-point number.
An expression whose value doesn’t change during the execution of a program, typically used in an assertion. See also: precondition, postcondition.
A family of code units (functions, classes, variables) that implement a set of related tasks.
loop variable
The variable that keeps track of the progress of the loop.
outer loop
A loop that contains another loop. See also: inner loop.
A variable named in the function’s declaration that is used to hold a value passed into the call. The term is often used interchangeably (and inconsistently) with argument.
A connection from the output of one program to the input of another. When two or more programs are connected in this way, they are called a “pipeline”.
A condition that a function (or other block of code) guarantees is true once it has finished running. Postconditions are often represented using assertions.
A condition that must be true in order for a function (or other block of code) to run correctly.
To re-introduce a bug that was once fixed.
An additive model that represents colors as combinations of red, green, and blue. Each color’s value is typically in the range 0..255 (i.e., a one-byte integer).
An array’s dimensions, represented as a vector. For example, a 5×3 array’s shape is (5,3).
silent failure
Failing without producing any warning messages. Silent failures are hard to detect and debug.
A regular subsequence of a larger sequence, such as the first five elements or every second element.
stack frame
A data structure that provides storage for a function’s local variables. Each time a function is called, a new stack frame is created and put on the top of the call stack. When the function returns, the stack frame is discarded.
standard input
A process’s default input stream. In interactive command-line applications, it is typically connected to the keyboard; in a pipe, it receives data from the standard output of the preceding process.
standard output
A process’s default output stream. In interactive command-line applications, data sent to standard output is displayed on the screen; in a pipe, it is passed to the standard input of the next process.
Short for “character string”, a sequence of zero or more characters.
syntax error
CHECKME: a programming error that occurs when statements are in an order or contain characters not expected by the programming language
test oracle
A program, device, data set, or human being against which the results of a test can be compared.
test-driven development
The practice of writing unit tests before writing the code they test.
CHECKME The classification of something in a program (for example, the contents of a variable) as a kind of number (e.g. floating-point, integer), string, or something else.
while loop
A loop that keeps executing as long as some condition is true. See also: for loop.