FLOOR
The FLOOR function determines an integer value from a floating point number that is lower than or equal to that number. It is always rounded down to the lower number.
The resulting number is of type LREAL and is therefore not limited to the value range of an integer variable.
Examples
FLOOR(2.8) = 2
FLOOR(-2.8) = -3
FUNCTION FLOOR : LREAL
Inputs
VAR_INPUT
lr_in : LREAL;
END_VARName | Type | Description |
|---|---|---|
lr_in | LREAL | Function parameters of type LREAL |
Comparison with other rounding functions
Similar functions: CEIL, TRUNC, LTRUNC
 | Unlike FLOOR, the LTRUNC function always determines the integral part of a number. For positive values, this number is lower than or equal to the input parameter, for negative values it is greater than or equal to the input parameter. |
Example results of various rounding functions
x | 0 | 0.4 | 0.5 | 0.6 | 1 | 1.4 | 1.5 | 1.6 | 1.78 |
|---|---|---|---|---|---|---|---|---|---|
FLOOR(x) | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 |
CEIL(x) | 0 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 2 |
LTRUNC(x) | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 |
TO_LINT(x) | 0 | 0 | 1 | 1 | 1 | 1 | 2 | 2 | 2 |
x | -1.78 | -1.6 | -1.5 | -1.4 | -1 | -0.6 | -0.5 | -0.4 |
|---|---|---|---|---|---|---|---|---|
FLOOR(x) | -2 | -2 | -2 | -2 | -1 | -1 | -1 | -1 |
CEIL(x) | -1 | -1 | -1 | -1 | -1 | 0 | 0 | 0 |
LTRUNC(x) | -1 | -1 | -1 | -1 | -1 | 0 | 0 | 0 |
TO_LINT(x) | -2 | -2 | -2 | -1 | -1 | -1 | -1 | 0 |
If you do not want to round to an integer value and instead want to round to a specific decimal place, this can be achieved by multiplying and dividing by a power of ten. The following example results show the rounding to the first decimal place.
x | 0 | 0.04 | 0.05 | 0.06 | 0.1 | 0.14 | 0.15 | 0.16 | 0.178 |
|---|---|---|---|---|---|---|---|---|---|
FLOOR(x * 10) / 10 | 0 | 0 | 0 | 0 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
CEIL(x * 10) / 10 | 0 | 0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 0.2 | 0.2 | 0.2 |
LTRUNC(x * 10) / 10 | 0 | 0 | 0 | 0 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
TO_LINT(x * 10) / 10.0 | 0 | 0 | 0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 0.2 | 0.2 |
x | -0.178 | -0.16 | -0.15 | -0.14 | -0.1 | -0.06 | -0.05 | -0.04 |
|---|---|---|---|---|---|---|---|---|
FLOOR(x * 10) / 10 | -0.2 | -0.2 | -0.2 | -0.2 | -0.1 | -0.1 | -0.1 | -0.1 |
CEIL(x * 10) / 10 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | 0 | 0 | 0 |
LTRUNC(x * 10) / 10 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | 0 | 0 | 0 |
TO_LINT(x * 10) / 10.0 | -0.2 | -0.2 | -0.2 | -0.1 | -0.1 | -0.1 | -0.1 | 0 |
Requirements
Development environment | Target system type | PLC libraries to include |
|---|---|---|
TwinCAT v3.0.0 | PC or CX (x86) | Tc2_Math |