vec_logical

Purpose

Returns a vector containing the results of performing a logical operation between a and b, using the truth table specified by c.

Syntax

d=vec_logical(a, b, c)

Result and argument types

The following table describes the types of the returned value and the function arguments.

d	a	b	c
`vector4double`	`vector4double`	`vector4double`	`int`, a value in the range of `[0x0, 0xF]`

Result value

The value of each element of the result is the result of the logical operation between the corresponding elements of a and b, using the truth table specified by c.

The following table shows how to read the truth table in c for the n^th element of a and b.

`a`[n]	`b`[n]	Binary result
False	False	`c`₀
True	False	`c`₁
False	True	`c`₂
True	True	`c`₃

The result value is calculated from the binary result.

Binary result	Result value
0	1.0 (True)
1	-1.0 (False)

Formula

If (a[n] < 0.0) AND (b[n] < 0.0)
  If (c₀ EQ 0), d[n]= -1.0
  Else d[n]= 1.0
If (a[n] ≥ 0.0) AND (b[n] < 0.0)
  If (c₁ EQ 0), d[n]= -1.0
  Else d[n]= 1.0
If (a[n] < 0.0) AND (b[n] ≥ 0.0)
  If (c₂ EQ 0), d[n]= -1.0
  Else d[n]= 1.0
If (a[n] ≥ 0.0) AND (b[n] ≥ 0.0)
  If (c₃ EQ 0), d[n]= -1.0
  Else d[n]= 1.0

Notes:

EQ is the equal operator.
In this function, NaN is considered to be less than zero.

Example

You can use the values for c from the following table to replicate some usual logical operators.

Binary	`c`	Operator
`0001`	`0x1`	AND
`0110`	`0x6`	XOR
`0111`	`0x7`	OR
`1000`	`0x8`	NOR
`1110`	`0xE`	NAND