9.3. Mathematical Functions and Operators

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9.3. Mathematical Functions and Operators

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 9.2, “Mathematical Operators” shows the available mathematical operators.

Table 9.2. Mathematical Operators

Operator

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

&

bitwise AND

91 & 15

11

|

bitwise OR

32 | 3

35

#

bitwise XOR

17 # 5

20

~

bitwise NOT

~1

-2

<<

bitwise shift left

1 << 4

16

>>

bitwise shift right

8 >> 2

2

The bitwise operators work only on integral data types, whereas the others are available for all numeric data types. The bitwise operators are also available for the bit string types bit and bit varying, as shown in Table 9.10, “Bit String Operators”.

Table 9.3, “Mathematical Functions” shows the available mathematical functions. In the table, dp indicates double precision. Many of these functions are provided in multiple forms with different argument types. Except where noted, any given form of a function returns the same data type as its argument. The functions working with double precision data are mostly implemented on top of the host system's C library; accuracy and behavior in boundary cases may therefore vary depending on the host system.

Table 9.3. 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(dp or numeric)

(same as input)

smallest integer not less than argument

ceil(-42.8)

-42

ceiling(dp or numeric)

(same as input)

smallest integer not less than argument (alias for ceil)

ceiling(-95.3)

-95

degrees(dp)

dp

radians to degrees

degrees(0.5)

28.6478897565412

exp(dp or numeric)

(same as input)

exponential

exp(1.0)

2.71828182845905

floor(dp or numeric)

(same as input)

largest integer not greater than argument

floor(-42.8)

-43

ln(dp or numeric)

(same as input)

natural logarithm

ln(2.0)

0.693147180559945

log(dp or numeric)

(same as input)

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

power(a dp, b dp)

dp

a raised to the power of b

power(9.0, 3.0)

729

power(a numeric, b numeric)

numeric

a raised to the power of b

power(9.0, 3.0)

729

radians(dp)

dp

degrees to radians

radians(45.0)

0.785398163397448

random()

dp

random value between 0.0 and 1.0

random()


round(dp or numeric)

(same as input)

round to nearest integer

round(42.4)

42

round(v numeric, s int)

numeric

round to s decimal places

round(42.4382, 2)

42.44

setseed(dp)

int

set seed for subsequent random() calls

setseed(0.54823)

1177314959

sign(dp or numeric)

(same as input)

sign of the argument (-1, 0, +1)

sign(-8.4)

-1

sqrt(dp or numeric)

(same as input)

square root

sqrt(2.0)

1.4142135623731

trunc(dp or numeric)

(same as input)

truncate toward zero

trunc(42.8)

42

trunc(v numeric, s int)

numeric

truncate to s decimal places

trunc(42.4382, 2)

42.43

width_bucket(op numeric, b1 numeric, b2 numeric, count int)

int

return the bucket to which operand would be assigned in an equidepth histogram with count buckets, an upper bound of b1, and a lower bound of b2

width_bucket(5.35, 0.024, 10.06, 5)

3

Finally, Table 9.4, “Trigonometric Functions” shows the available trigonometric functions. All trigonometric functions take arguments and return values of type double precision.

Table 9.4. 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