6.3. 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 6-2 shows the available mathematical operators.

Table 6-2. Mathematical Operators

+ addition2 + 35
- subtraction2 - 3-1
* multiplication2 * 36
/ division (integer division truncates results)4 / 22
% modulo (remainder)5 % 41
^ exponentiation2.0 ^ 3.08
|/ square root|/ 25.05
||/ cube root||/ 27.03
! factorial5 !120
!! factorial (prefix operator)!! 5120
@ absolute value@ -5.05
& binary AND91 & 1511
| binary OR32 | 335
# binary XOR17 # 520
~ binary NOT~1-2
<< binary shift left1 << 416
>> binary shift right8 >> 22

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

B'10001' & B'01101'00001
B'10001' | B'01101'11101
B'10001' # B'01101'11110
~ B'10001'01110
B'10001' << 301000
B'10001' >> 200100

Table 6-4 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 datatype 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 6-4. Mathematical Functions

FunctionReturn TypeDescriptionExampleResult
abs(x)(same as x)absolute valueabs(-17.4)17.4
cbrt(dp)dpcube rootcbrt(27.0)3
ceil(dp or numeric)(same as input)smallest integer not less than argumentceil(-42.8)-42
degrees(dp)dpradians to degreesdegrees(0.5)28.6478897565412
exp(dp or numeric)(same as input)exponentialexp(1.0)2.71828182845905
floor(dp or numeric)(same as input)largest integer not greater than argumentfloor(-42.8)-43
ln(dp or numeric)(same as input)natural logarithmln(2.0)0.693147180559945
log(dp or numeric)(same as input)base 10 logarithmlog(100.0)2
log(b numeric, x numeric)numericlogarithm to base blog(2.0, 64.0)6.0000000000
mod(y, x)(same as argument types)remainder of y/xmod(9,4)1
pi()dp"Pi" constantpi()3.14159265358979
pow(x dp, e dp)dpraise a number to exponent epow(9.0, 3.0)729
pow(x numeric, e numeric)numericraise a number to exponent epow(9.0, 3.0)729
radians(dp)dpdegrees to radiansradians(45.0)0.785398163397448
random()dprandom value between 0.0 and 1.0random() 
round(dp or numeric)(same as input)round to nearest integerround(42.4)42
round(v numeric, s integer)numericround to s decimal placesround(42.4382, 2)42.44
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 rootsqrt(2.0)1.4142135623731
trunc(dp or numeric)(same as input)truncate toward zerotrunc(42.8)42
trunc(v numeric, s integer)numerictruncate to s decimal placestrunc(42.4382, 2)42.43

Finally, Table 6-5 shows the available trigonometric functions. All trigonometric functions take arguments and return values of type double precision.

Table 6-5. Trigonometric Functions

acos(x)inverse cosine
asin(x)inverse sine
atan(x)inverse tangent
atan2(x, y)inverse tangent of x/y