mirror of
https://github.moeyy.xyz/https://github.com/trekhleb/javascript-algorithms.git
synced 2024-12-25 22:46:20 +08:00
Update BitWise Operation README.
This commit is contained in:
parent
3f963ccc21
commit
7f189498cf
@ -91,24 +91,30 @@ inverting all of the bits of the number and adding 1 to it.
|
||||
|
||||
> See `switchSign` function for further details.
|
||||
|
||||
#### Multiply
|
||||
#### Multiply Two Numbers
|
||||
|
||||
This method multiplies two numbers(integer) using bitwise operators. This method is based on that "Every number can be denoted as the sum of powers of 2".
|
||||
This method multiplies two integer numbers using bitwise operators.
|
||||
This method is based on that "Every number can be denoted as the sum of powers of 2".
|
||||
|
||||
```
|
||||
Let us take two numbers number1 and number2.
|
||||
The main idea of bitwise multiplication is that every number may be split
|
||||
to the sum of powers of two:
|
||||
|
||||
number1 * number2 = number1 * (Representation in Base 2)
|
||||
I.e.
|
||||
|
||||
Let us take number2 = 8 = 0b 1000
|
||||
|
||||
number1 * number2 = number1 * (1*8 + 0*4 + 0*2 + 0*1)
|
||||
= number1 * 1 * (1<<3) + number1 * 0 * (1<<2) + number1 * 0 * (1<<1) + number1 * 0 * (1<<0)
|
||||
= (number1<<3) * 1 + (number1<<2) * 0 + (number1<<1) * 0 + (number1<<0) * 0
|
||||
```text
|
||||
19 = 2^4 + 2^1 + 2^0
|
||||
```
|
||||
|
||||
Then multiplying number `x` by `19` is equivalent of:
|
||||
|
||||
> See `multiply` function for further details.
|
||||
```text
|
||||
x * 19 = x * 2^4 + x * 2^1 + x * 2^0
|
||||
```
|
||||
|
||||
Now we need to remember that `x * 2^4` is equivalent of shifting `x` left
|
||||
by `4` bits ()`x << 4`).
|
||||
|
||||
> See `multiplyUnsigned` function for further details.
|
||||
|
||||
## References
|
||||
|
||||
|
@ -2,7 +2,7 @@
|
||||
* Multiply to unsigned numbers using bitwise operator.
|
||||
*
|
||||
* The main idea of bitwise multiplication is that every number may be split
|
||||
* to the sum of posers of two:
|
||||
* to the sum of powers of two:
|
||||
*
|
||||
* I.e. 19 = 2^4 + 2^1 + 2^0
|
||||
*
|
||||
|
Loading…
Reference in New Issue
Block a user