| DSP Blockset | |
Find the minimum values in an input or sequence of inputs.
Library
Description
The Minimum block identifies the value and position of the smallest element in each column of the input, or tracks the minimum values in a sequence of inputs over a period of time. The Mode parameter specifies the block's mode of operation, and can be set to Value, Index, Value and Index, or Running.
Value Mode
When Mode is set to Value, the block computes the minimum value in each column of the M-by-N input matrix u independently at each sample time.
val = min(u) % Equivalent MATLAB code
For convenience, length-M 1-D vector inputs and sample-based length-M row vector inputs are both treated as M-by-1 column vectors.
The output at each sample time, val, is a 1-by-N vector containing the minimum value of each column in u. For complex inputs, the block selects the value in each column that has the minimum magnitude, min(abs(u)), as shown below.
The frame status of the output is the same as that of the input.
Index Mode
When Mode is set to Index, the block computes the minimum value in each column of the M-by-N input matrix u,
[val,idx] = min(u) % Equivalent MATLAB code
and outputs the sample-based 1-by-N index vector, idx. Each value in idx is an integer in the range [1 M] indexing the minimum value in the corresponding column of u.
As in Value mode, length-M 1-D vector inputs and sample-based length-M row vector inputs are both treated as M-by-1 column vectors.
If a minimum value occurs more than once in a particular column of u, the computed index corresponds to the first occurrence. For example, if the input is the column vector [-1 2 3 2 -1]', the computed index of the minimum value is 1 rather than 5.
Value and Index Mode
When Mode is set to Value and Index, the block outputs both the vector of minima, val, and the vector of indices, idx.
Running Mode
When Mode is set to Running, the block tracks the minimum value of each channel in a time-sequence of M-by-N inputs. For sample-based inputs, the output is a sample-based M-by-N matrix with each element yij containing the minimum value observed in element uij for all inputs since the last reset. For frame-based inputs, the output is a frame-based M-by-N matrix with each element yij containing the minimum value observed in the jth column of all inputs since the last reset, up to and including element uij of the current input.
If the Reset port parameter is set to Non-zero sample, the optional Rst port is enabled and the block resets the running minimum when the scalar input at the Rst port is nonzero. (The Rst port can be disabled by setting the Reset port parameter to None.) For sample-based inputs, the running minimum for each channel is initialized to the value in the corresponding channel of the current input. For frame-based inputs, the running minimum for each channel is initialized to the earliest value in each channel of the current input.
As in the other modes, length-M 1-D vector inputs and sample-based length-M row vector inputs are both treated as M-by-1 column vectors.
Example
The Minimum block in the model below calculates the running minimum of a frame-based 3-by-2 (two-channel) matrix input. The running minimum is reset at t=2 by an impulse to the block's Rst port.
The Minimum block has the following settings:
The Signal From Workspace block has the following settings:
u1/33u = [6 1 3 -7 2 5 8 0 -1 -3 2 1;1 3 9 2 4 2 6 2 5 0 4 17]'
The Discrete Impulse block has the following settings:
211The block's operation is shown in the figure below.
Dialog Box
Rst input port when set to Non-zero sample, and disables the Rst input port when set to None.See Also
| Maximum |
DSP Blockset |
| Mean |
DSP Blockset |
| MinMax |
Simulink |
| Histogram |
DSP Blockset |
min |
MATLAB |
| | Median | Modified Covariance AR Estimator | |