Exclude Data — Control Systems/Curve Fitting

Exclude Data

Control Systems / Curve Fitting

Marks the sample arriving now as one a downstream fit should ignore. The output is the flag itself: 1 when the sample is excluded and 0 when it is kept – the same polarity as the logical vector excludedata returns, so a script's outliers and this block's excl mean the same thing.

Four rules, and they are the whole of the MATLAB function: domain tests the predictor against a pair of bounds, range tests the response, box tests both, and indices tests the sample's position in the run. Feed the flag to a Switch to act on it, or to a Signal Recorder to count what a fit threw away.

Ports

• x – the predictor, scalar. Read by domain and box; the other two rules ignore its value but still need the port wired.
• y – the response, scalar. Read by range and box, and ignored by the other two in the same way.
• excl – the flag, scalar: 1 excluded, 0 kept. Its size is fixed and follows neither input.

Parameters

• Exclusion Rule – which test is applied. Four values, named as MATLAB names them:
  • domain – excluded when x < X₀ or x > X₁.
  • range – excluded when y < Y₀ or y > Y₁.
  • box – the default: excluded when either of the two above holds, i.e. when the pair falls outside the rectangle.
  • indices – excluded when the sample's one-based ordinal appears in Excluded Sample Indices. Neither input's value is read.
• X Bounds – the pair [X₀ X₁] a predictor must stay inside, as a two-element row or column. Read by domain and box. Both comparisons are strict, so a sample exactly on a bound is kept.
• Y Bounds – the pair [Y₀ Y₁] for the response, with the same shape and the same strictness. Read by range and box.
• Excluded Sample Indices – the ordinals to exclude under indices, as a vector of whole numbers from 1 upwards; up to 64 of them, because the tests are unrolled at export. Duplicates and order do not matter, and an empty list excludes nothing.
• Sampling Time (s) – zero or less inherits the solver's rate; a positive value runs the block at that period.

Code export

All ten targets: Python, MATLAB, Java, Rust, C, C++, VHDL, Verilog, SystemVerilog and PLC Structured Text.

The rule and its constants are structural and are inlined into the comparisons at export time rather than exposed as tunable parameters: the rule decides which comparisons the core contains at all, which no runtime parameter can do. Re-export after changing any of them.

The three HDL targets are genuine synthesizable Q16.16, and unusually cheaply so: nothing here is arithmetic on the signal, only comparisons against constants and an integer counter. One caveat follows from the format rather than from the block – a hardware port delivers a value already quantized to about 1.5×10⁻⁵, so a sample sitting within one quantum of a bound can fall on the other side of it there than in the simulation. It matters only for a bound a signal repeatedly lands exactly on.

Simulink bridge

None (Support::None). excludedata is a Curve Fitting Toolbox function, and that toolbox ships no Simulink library at all, so there is no path a diagram could name. The bridge reports this block rather than dropping it silently, and it therefore has no parity testbench; code export verification still covers it across all ten languages. No configuration of it crosses either, including "Sampling Time (s)", which has no counterpart to be written to.

Notes

• Stateful, and discrete by nature (setDiscreteOnlyBlock(true)): the sample ordinal advances once per executed step.
• The ordinal is one-based and counts this block's own steps, starting at 1 for the first. It advances under every rule, not only under indices, so switching rules renumbers nothing. A block given its own positive Sampling Time (s) counts its own ticks, not the solver's.
• Both inputs are required under every rule. The port list is fixed when the block is built and cannot follow a configuration value, so domain still shows a y port and range still shows an x port. Wire the unread one to anything; its value is not read.
• A bound pair is not checked for order. Giving X₀ > X₁ excludes every sample, which is what the two comparisons say and what MATLAB does with the same input.
• It marks, it does not remove. A stream has no way to delete a sample – every block downstream still gets one value per step – so the flag is what a consumer acts on. That is also why the block pairs naturally with Switch.
• Algebraic in its inputs. The flag depends only on the current x, y and ordinal; no past sample influences it.
• No state space. The map is a comparison, not a linear system, so the block carries none and model reduction correctly declines to merge it.