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Mathematical operators are provided for many PostgreSQL
types. For types without common mathematical conventions for all possible permutations (e.g.,
date/time types) we describe the actual behavior in subsequent sections.
Table
6-2 shows the available mathematical operators.
Table 6-2. Mathematical Operators
| Name |
Description |
Example |
Result |
| + |
addition |
2 + 3 |
5 |
| - |
subtraction |
2 - 3 |
-1 |
| * |
multiplication |
2 * 3 |
6 |
| / |
division (integer division truncates results) |
4 / 2 |
2 |
| % |
modulo (remainder) |
5 % 4 |
1 |
| ^ |
exponentiation |
2.0 ^ 3.0 |
8 |
| |/ |
square root |
|/ 25.0 |
5 |
| ||/ |
cube root |
||/ 27.0 |
3 |
| ! |
factorial |
5 ! |
120 |
| !! |
factorial (prefix operator) |
!! 5 |
120 |
| @ |
absolute value |
@ -5.0 |
5 |
| & |
binary AND |
91 & 15 |
11 |
| | |
binary OR |
32 | 3 |
35 |
| # |
binary XOR |
17 # 5 |
20 |
| ~ |
binary NOT |
~1 |
-2 |
| << |
binary shift left |
1 << 4 |
16 |
| >> |
binary shift right |
8 >> 2 |
2 |
The "binary" operators are also available for the bit
string types BIT and BIT VARYING, as shown in Table
6-3. Bit string arguments to &, |,
and # must be of equal length. When bit shifting, the original length
of the string is preserved, as shown in the table.
Table 6-3. Bit String Binary Operators
| Example |
Result |
| B'10001' & B'01101' |
00001 |
| B'10001' | B'01101' |
11101 |
| B'10001' # B'01101' |
11110 |
| ~ B'10001' |
01110 |
| B'10001' << 3 |
01000 |
| B'10001' >> 2 |
00100 |
Table
6-4 shows the available mathematical functions. In the table, dp
indicates double precision. The functions exp,
ln, log, pow, round (1 argument), sqrt, and trunc (1 argument) are also available for the type numeric
in place of double precision. Functions returning a numeric
result take numeric input arguments, unless otherwise specified. Many of
these functions are implemented on top of the host system's C library; accuracy and behavior
in boundary cases could therefore vary depending on the host system.
Table 6-4. Mathematical Functions
| Function |
Return Type |
Description |
Example |
Result |
| abs(x) |
(same as x) |
absolute value |
abs(-17.4) |
17.4 |
| cbrt(dp) |
dp |
cube root |
cbrt(27.0) |
3 |
| ceil(numeric) |
numeric |
smallest integer not less than argument |
ceil(-42.8) |
-42 |
| degrees(dp) |
dp |
radians to degrees |
degrees(0.5) |
28.6478897565412 |
| exp(dp) |
dp |
exponential |
exp(1.0) |
2.71828182845905 |
| floor(numeric) |
numeric |
largest integer not greater than argument |
floor(-42.8) |
-43 |
| ln(dp) |
dp |
natural logarithm |
ln(2.0) |
0.693147180559945 |
| log(dp) |
dp |
base 10 logarithm |
log(100.0) |
2 |
| log(b
numeric, x numeric) |
numeric |
logarithm to base b |
log(2.0, 64.0) |
6.0000000000 |
| mod(y,
x) |
(same as argument types) |
remainder of y/x |
mod(9,4) |
1 |
| pi() |
dp |
"Pi" constant |
pi() |
3.14159265358979 |
| pow(e
dp, n dp) |
dp |
raise a number to exponent e |
pow(9.0, 3.0) |
729 |
| radians(dp) |
dp |
degrees to radians |
radians(45.0) |
0.785398163397448 |
| random() |
dp |
value between 0.0 to 1.0 |
random() |
|
| round(dp) |
dp |
round to nearest integer |
round(42.4) |
42 |
| round(v
numeric, s integer) |
numeric |
round to s decimal
places |
round(42.4382, 2) |
42.44 |
| sign(numeric) |
numeric |
sign of the argument (-1, 0, +1) |
sign(-8.4) |
-1 |
| sqrt(dp) |
dp |
square root |
sqrt(2.0) |
1.4142135623731 |
| trunc(dp) |
dp |
truncate toward zero |
trunc(42.8) |
42 |
| trunc(numeric,
r integer) |
numeric |
truncate to s decimal
places |
trunc(42.4382, 2) |
42.43 |
Finally, Table
6-5 shows the available trigonometric functions. All trigonometric functions have
arguments and return values of type double precision.
Table 6-5. Trigonometric Functions
| Function |
Description |
| acos(x) |
inverse cosine |
| asin(x) |
inverse sine |
| atan(x) |
inverse tangent |
| atan2(x,
y) |
inverse tangent of x/y |
| cos(x) |
cosine |
| cot(x) |
cotangent |
| sin(x) |
sine |
| tan(x) |
tangent |
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