Offset
Truncate vectors by removing or keeping beginning or ending values
Libraries:
DSP System Toolbox /
Signal Operations
Description
The Offset block removes or keeps values from the beginning or end of the input vectors. The number of values to remove or keep is determined by the offset value that you specify through the O ports (O1, O2, … ). The length of the truncated vector is determined by the Output port length and Output length parameters. The Number of input dataoffset pairs parameter determines the number of input dataoffset pairs.
Examples
Truncate Data Vector Using Offset Block
Truncate data vector using Offset block in all the four modes.
Ports
Input
In1 — First input data
scalar  vector
Specify the first input data as a scalar or a vector. The inputs to the In ports (In1, In2, … ) must be of the same size and data type.
If the input is fixed point, it must be a signed integer or a signed fixed point value with a poweroftwo slope and zero bias.
Data Types: single
 double
 int8
 int16
 int32
 fixed point
Complex Number Support: Yes
O1 — First offset value
integer
Specify the offset value that the block uses to truncate the first input data as an integer. The offset value determines the number of samples the block removes or keeps at the beginning or at the end of the first data.
The inputs to the O ports (O1, O2, … ) must have the same data type. The block rounds any offset value that is a noninteger value to the nearest integer value. If the offset value is out of the [0 N] range, then the Action for out of range offset value parameter determines how the block behaves. N is the input vector length.
Data Types: single
 double
 int8
 int16
 int32
 uint8
 uint16
 uint32
In2 — Second input data
scalar  vector
Specify the second input data as a scalar or a vector. The inputs to the In ports (In1, In2, … ) must be of the same size and data type.
If the input is fixed point, it must be a signed integer or a signed fixed point value with a poweroftwo slope and zero bias.
Data Types: single
 double
 int8
 int16
 int32
 fixed point
Complex Number Support: Yes
O2 — Second offset value
integer
Specify the offset value that the block uses to truncate the second input data as an integer. The offset value determines the number of samples the block removes or keeps at the beginning or at the end of the second data.
The inputs to the O ports (O1, O2, … ) must have the same data type. The block rounds any offset value that is a noninteger value to the nearest integer value. If the offset value is out of the [0 N] range, then the Action for out of range offset value parameter determines how the block behaves. N is the input vector length.
Data Types: single
 double
 int8
 int16
 int32
 uint8
 uint16
 uint32
Output
Out1 — First truncated data
scalar  vector
The block returns the truncated data as a scalar or a vector. The
length of the truncated data depends on the Output port
length and the Output length
parameters. If Output port length is set to
Same as input
, the truncated data has the
same size as the input data. If Output port length
is set to Userdefined
, then the
Output length parameter determines the length
of the output data.
There is one output port for each pair of In and O ports.
The truncated output has the same data type as the input data. When the output is fixedpoint, it is signed only.
Data Types: single
 double
 int8
 int16
 int32
 fixed point
Complex Number Support: Yes
Out2 — Second truncated data
scalar  vector
The block returns the truncated data as a scalar or a vector. The
length of the truncated data depends on the Output port
length and the Output length
parameters. If Output port length is set to
Same as input
, the truncated data has the
same size as the input data. If Output port length
is set to Userdefined
, then the
Output length parameter determines the length
of the output data.
There is one output port for each pair of In and O ports.
The truncated output has the same data type as the input data. When the output is fixedpoint, it is signed only.
Data Types: single
 double
 int8
 int16
 int32
 fixed point
Complex Number Support: Yes
Parameters
Mode — Specify which values to discard and which values to keep
Remove beginning
samples
(default)  Remove ending samples
 Keep beginning samples
 Keep ending samples
Use this parameter to specify which values the block discards and which values the block keeps from the input vector.
Select from the following:
Remove beginning samples
–– Discard the initial values of a vector.Remove ending samples
–– Discard the final values of a vector.Keep beginning samples
–– Retain the initial values of a vector.Keep ending samples
–– Retain the final values of a vector.
Number of input dataoffset pairs — Number of input dataoffset pairs
2
(default)  positive integer
Use the Number of input dataoffset pairs parameter to specify the
number of inputs to the block. The number of input ports is twice the scalar
value you specify in this parameter. For example, if you enter
3
, input ports In1,
O1, In2,
O2, In3, and
O3 appear on the block.
Output port length — Mode to specify output port length
Same as input
(default)  Userdefined
Use this parameter to specify the length of the output vectors. If you select
Same as input
, the output vectors have the
same length as the input vectors. If you select
Userdefined
, you can enter the desired
length in the Output length parameter.
Output length — Desired length of output vectors
9
(default)  positive integer
Enter a scalar that represents the desired length of the output vectors. If the desired output length that you specify is greater than the number of values that the block extracts from the input vector, the block zeropads the end of the vector to reach the length that you specify.
Dependencies
This parameter is visible only if you set the Output port
length parameter to
Userdefined
.
Action for out of range offset value — Action for out of range offset value
Clip
(default)  Clip and warn
 Error
Use this parameter to determine how the block behaves when an offset value is not in the range such that 0 ≤ offset value ≤ N, where N is the input vector length.
Clip
–– Offset values less than 0 are set to 0 and offset values greater than N are set to N.Clip and warn
–– Offset values less than 0 are set to 0 and offset values greater than N are set to N. In addition, the block displays a warning message.Error
–– Simulation stops and the block displays an error when the offset values or out of range.
Block Characteristics
Data Types 

Direct Feedthrough 

Multidimensional Signals 

VariableSize Signals 

ZeroCrossing Detection 

Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
Generated code relies on the memcpy
or
memset
function (string.h
) under certain
conditions.
Version History
Introduced before R2006a
See Also
Detrend  Pad  DC Blocker  Unwrap
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