PostgreSQL 8.2.6 Documentation  

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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 92 shows the available mathematical operators.
Table 92. 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 910 .
Table 93 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 93. 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  "π" 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 (value between 0 and 1.0)  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, in the range b1 to b2  width_bucket(5.35, 0.024, 10.06, 5)  3 
Finally, Table 94 shows the available trigonometric functions. All trigonometric functions take arguments and return values of type double precision .