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The Art of Mathematics

Help 6.5

abs — absolute value function

1. Definition

Absolute value function is defined as

|x| = x for x ≥ 0;
|x| = −x for x < 0.

2. Graph

Absolute value function is defined everywhere on real axis. Its graph is depicted below — fig. 1.

[画像:Fig. 1. Graph y = |x|.] Fig. 1. Graph of the absolute value function y = |x|.

Function codomain is non-negative half of the real axis: [0, +∞).

3. Identities

Function is symmetrical:

|−x| = |x|

Sum and difference of arguments:

|x + y| = |x| + |y|, if signx = signy
|x + y| = ||x| − |y||, if signx ≠ signy
|x − y| = ||x| − |y||, if signx = signy
|x − y| = |x| + |y|, if signx ≠ signy

Product and ratio of arguments:

|xy| = |x||y|
|x /y| = |x| /|y|

4. Derivative and indefinite integral

Absolute value derivative:

|x|′ = 1 for x > 0;
|x|′ = −1 for x < 0.

For 0 the derivative is undefined.

Indefinite integral of the absolute value:

∫ |x| dx = signx x²/2 + C

where sign is a signum function and C is an arbitrary constant.

5. How to use

To get absolute value of the number:

abs(−1);

To calculate absolute value of the complex number:

abs(−1+i);

To get absolute value of the current result:

abs(rslt);

To get absolute value of the number z in calculator memory:

abs(mem[z]);

6. Support

Absolute value of the real number is supported in free version of the Librow calculator.

Absolute value of the complex number is supported in professional version of the Librow calculator.

Function 1
√ or sqrt

Function 2
Γ or Gamma

Function 3
∏ or Prod

Function 4
∑ or Sum

Function 5
abs

Function 6
arccos

Function 7
arccot or arcctg

Function 8
arccsc or arccosec

Function 9
arcosh or arch

Function 10
arcoth or arcth

Function 11
arcsch

Function 12
arcsec

Function 13
arcsin

Function 14
arctan or arctg

Function 15
arg

Function 16
arsech or arsch

Function 17
arsinh or arsh

Function 18
artanh or arth

Function 19
ceil

Function 20
conj

Function 21
cos

Function 22
cosh or ch

Function 23
cot or ctg

Function 24
coth or cth

Function 25
csc or cosec

Function 26
csch

Function 27
exp

Function 28
fact

Function 29
floor

Function 30
I

Function 31
im

Function 32
J

Function 33
K

Function 34
ln

Function 35
log or lg

Function 36
^

Function 37
rand

Function 38
re

Function 39
sec

Function 40
sech

Function 41
sign

Function 42
sin

Function 43
sinh or sh

Function 44
tan or tg

Function 45
tanh or th

Function 46
Y

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