Comparison of Functions

Here is the beginnings of my notes comparing functions among different languages (Java, MS-Office/Access, MS-SQL, Oracle).

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Function Calls

A function is a block of code with a defined name that performs a process.

Official C# terminology states that a function member includes not just methods, but also indexers, operators, constructors, destructors, and other non-data members of a class or struct.

In this function call foo(bar1,bar2);

• parentheses enclose the arguments supplied to the function.
• a comma separate arguments named bar and bar2.
• a semi-colon terminates the statement.

Syntax:


return_type function_name (parameter1, parameter2) {
    // body of method (Java statements)
}
Example:
int AORR (int length, int width) {
    return length * width
}

In this C# programming example:

System.Console.Write("Hello");

invokes the write method as an object from class Console stored within a project namespace System.

With Java, use the "Math." library prefix when using Java's native Math library's methods: abs, ceil, floor, max, min, random, round, sin, cos, tan, sqrt. For example: result = Math.random();

The word "function" is used in two contexts: users refer to application functions such as "create new account", whereas developers write programmatic functions such as "instantiate component xyz" or "store segment abc".

The NIST Dictionary of Algorithms and Data Structures

Overloading Java Functions

Overloading is when a function name is used with different signatures: different number of arguments or a different sequence of argument datatypes.

Aggregate Functions

Library	Function	Return Type	Parameters	Description of value(s) returned
	Least	-	--	In Oracle: the smallest value among columns in the same row.
	greatest	-	--	In Oracle: the largest value among columns in the same row.
	avg	value	--	In Oracle: the average of value for a group of rows
Math.	max	-	-	Oracle: Maximum of all value for groups of rows Java: Returns a value equal to the greater of the two arguments input. The datatype of the returned value corresponds to that of the arguments.
Math.	min	-	-	Oracle: Minimum of all values for groups of rows Java: Returns a value equal to the lesser of the two arguments input. The datatype of the returned value corresponds to that of the arguments.
	Count	-	-	Oracle: Count of rows of columns.

Numeric Math Functions

static long abs(long x);

Library	Function	Return Type	Parameters	Description of value(s) returned
	vsize	text, num, date, ROWID, etc.	--	In Oracle: the number of bytes occupied by the value
	sign	numVal	--	In Oracle: 1 if numVal is positive, -1 if numVal is negative, 0 if zero.
Math.	abs	int/long/float/double	int/long/float/double numVal	The absolute (positive) value. Returns the same data type as the input argument. (a long if the argument is long, etc.)
Math.	round	int/long	float/double numVal	Java rounds a number to the nearest whole number. Oracle adds a parameter for decimal precision.
Math.	ceil	double	double numVal	The smallest whole number greater than or equal to argument numVal.
Math.	floor	double	double numVal	The largest whole number less than or equal to numVal.
	mod	--	float/double numVal	The modulus (remainder) for a number and its divisor from a division operation.
	pow	double	double x, double y	x raised to the power of y.
Math.	sqrt	double	double numValue	Returns the square root. If the argument is negative, it returns “NaN” (Not a Number).
	exp	double	double numValue	Returns the exponential constant e raised to the power of a double value
	pow	double	double x, double y	Returns the value of the first argument xraised to the power of the second argument y
	log	double	double numValue	Returns the natural logarithm (base e) of a double value
Math.	random	double	None	A random number between 0 and 1. Simulates the roll of dice in a board game.
	toRadians	-	numValue	Converts into radians an angle specified in degrees.
	toDegrees	-	numValue	Converts into degrees an angle specified in radians.

The absolute value is used to determine whether a number is odd or even. In Transac-SQL:

SELECT
x,
CASE WHEN ABS(x) % 2 = 1
THEN 'odd'
ELSE 'even'
END
FROM table

In VBScript:

<%
x = 5
stat = "even"
SELECT CASE abs(x) mod 2
CASE 1: stat = "odd"
END SELECT
Response.write x & " is " & stat
%>

In JScript:

<script language='JScript' runat=server>
var x = 5;
var stat = "even";
switch(Math.abs(x) % 2) {
case 1 : stat = "odd";
}
Response.Write(x.toString() + " is " + stat);
</script>

Trigonometric Functions

Angles within these trig functions are specified in radians as rather than in degrees.

Library	Function	Return Type	Parameters	Description
	acos	double	double angle	Returns the arc cosine of an angle, in the range of 0.0 through pi
	asin	double	double angle	Returns the arc sine of an angle, in the range of -pi/2 through pi/2
	atan2	double	double x, double y	Returns the arc tangent of an angle, in the range of -pi/2 through pi/2
	atan	double	double angle	Converts rectangular coordinates (b, a) to polar (r, theta)
Math.	cos	double	double angle	Returns the trigonometric cosine of an angle in radians.
Math.	sin	double	double angle	The sine of the angle specified in radians.
Math.	tan	double	double angle	The tangent of the angle specified in radians.

Text Character Functions

Library	Function	Return Type	Parameters	Description of return value
	length	number	number	In Oracle: Returns the number of characters in the column.
	initcap	text	--	In Oracle: Initial caplitalize (the first letter of each word in) variables.
	lpad	text	--	In Oracle: Pre-pends additional filler characters on the left of data in a column.
	rpad	text	--	In Oracle: Appends additional filler characters on the right of data in a column. Typically used in formatting fixed-space reports: dbms_output.put_line( rpad('TABLESPACE',60,' ') ) || rpad('TOTAL(M)',10,' ') || rpad('FREE(M)',10,' '));
	ltrim rtrim	text	--	In Oracle: Removes blanks from the left or right of a column.
	substr	text	1.column 2.starting position 3.number of positions	In Oracle: Removes blanks from the left or right of a column.
	trunc(sysdate)	text	--	In Oracle: Truncates (removes) the time portion of what is returned from the sysdate system variable.
	to_char	text	--	In Oracle: Converts to data type values in other data types (such as date and numeric).

Lowe Lum Carlson Systems' Oracle SQL 8i Tutorials Lesson #11 - Character Functions

Constants

The Math class provides two double type constants (values which never change):
• Math.PI ~=3.14 -- The mathematical constant, lower-case Greek letter pi ( π ).
• Math.E ~=2.718281828459045 -- Leonhard Euler's number e, the base of natural logarithms, such that ln(e^1) = 1
• No Phi ~=1.618 -- the basis for the Golden Rectangles and Spirals found in nature (in sunflowers, nautilus shells, and the formation of galaxies).