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Inflection Solver

Inflection solver node

The Inflection solver signals when an indicator’s slope reverses: the turning point, or inflection point.

Long when the slope turns from falling to rising, Short when it turns from rising to falling. With price as the Input, it marks price reversals.

Properties tab

Property Inspector tabs, with the Properties tab selected

The essential settings for the node.

Modifiers

Buttons for the most common output modifiers. They change only the selected instance of a node on a Logic Board, so they appear only when a node is selected there, not when a solver is selected in the Solvers panel. That keeps the solver’s original output unchanged everywhere else it’s used, much like changing an SMA’s plot color on one chart leaves it unchanged on your other charts.

Modifiers: the Enabled, Invert and Swap buttons
ButtonWhat it does
EnableTurns the node on or off. When it’s off, the node is left out of the system’s calculations. It still looks connected on the Logic Board, but it’s ignored.
InvertInverts the node’s output. The same calculation as the Inverter function node, without its extra options.
SwapSwaps the outputs: Long becomes Short and Short becomes Long. The same as the Long/Short Modifier function node with Mode: Swap.

Global Properties

These settings apply to every instance of the solver: change one instance and they all change. To change just one, make a copy of the solver. The copy is a separate solver, with a number added to the end of its name.

Behavior

Turns off the Long or the Short output.

Behavior: the Evaluate setting
SettingWhat it does
EvaluateWhich outputs the solver calculates.
Both: Long and Short.
Long only: only Long; the Short output is removed.
Short only: only Short; the Long output is removed.

Input

What the solver evaluates. Choose a data type in the Type menu; the settings below it change to match.

Input with Type set to Indicator Value: Indicator and Displacement settings
TypeWhat it evaluates
Indicator ValueAny installed indicator with a plot or Series<T> output, chosen in the Select Indicator window. The default and most used type. Displacement reads the value from a number of bars back.
PriceA bar price (Open, High, Low, Close, or the Body Top, Median or Bottom), optionally processed over a lookback period.
VolumeThe current bar’s volume.
Swing Point PricesPrices from the latest swing highs and lows.
Linear Regression ChannelThe upper, middle or lower line of a regression channel.
Fixed ValueA single value that never changes. Only useful for solvers with two inputs, such as Comparison.

Every type and its settings in full: Data type selection.

Settings

Settings: Lookback Period
SettingWhat it does
Lookback PeriodHow many bars back to look for an inflection. 1 is the current bar only, 2 includes the previous bar, and so on.

Output

Output: Slope In Direction, No Inflection, Output Decreases as Inflection Ages By, Slope Against Direction
SettingWhat it does
Slope In DirectionThe Long output when the slope turns from falling to rising, and the Short output when it turns from rising to falling.
No InflectionThe value of the Long output and the Short output when there is no inflection.
Output Decreases as Inflection Ages ByReduces the output by this amount on each bar after the inflection, until it reaches zero or the Lookback Period ends.
Slope Against DirectionThe opposite of Slope In Direction: the Short output when the slope turns up, and the Long output when it turns down.

Options tab

Property Inspector tabs, with the Options tab selected

Secondary settings shared by all nodes.

Weight

Changes the node’s final output value. Only needed when designing a fuzzy logic system, or a fuzzy logic part of a system.

How Weight works

Weight changes only the selected instance of a node on a Logic Board. So the controls appear only when a node is selected there, not when a solver is selected in the Solvers panel: a solver’s original output can’t be changed globally.

ControlWhat it does
Multiply OutputMultiplies the node’s internal Long and Short values (set by the Output Rules on the Properties tab) by this number. The final output still can’t go above 1 (see Slider).
SliderLimits the final output to between 0 and 1. The left handle sets a minimum output, given whether or not the condition is true. The right handle sets the maximum; the output is capped there.
Hedge OperationApplies a formula to the internal value.
None: unchanged.
Very: squares it (value²).
Somewhat: takes the square root (√value).

Example: two out of three

Three solvers check three indicator conditions, but only two need to be true. Connect them to an Additive logic node and set each solver’s maximum (the slider’s right handle) to 0.5. When any two are true, the Additive node adds 0.5 + 0.5 + 0 = 1, which means the two-out-of-three condition is met.

Description

Free text for describing what the node does or what it’s for. The Description is shared by every instance of the node, unlike Weight, which is set per instance.

Help tab

Property Inspector tabs, with the Help tab selected

Shows this page for the selected node, inside BloodHound. Click the node’s image at the top of the page to open it in a bigger window. The built-in web viewer needs NinjaTrader 8.0.26.0 or newer.

Tutorial video

It shows BloodHound v1, but the settings and how they work are the same.

Examples

Example 1: The basics

Signals each time the SMA changes direction.

Settings and chart

Settings

  • Add the Inflection solver to the Logic Board and connect it to the Result node.

Result

A signal whenever the SMA reverses direction.

Example 2A: Price reversals

Marks each change of direction of the bars, here BacktestRenko bars. It works on other bar types too.

Settings and chart

Settings

  • Add the Inflection solver to the Logic Board and connect it to the Result node.
  • Set Input » Type to Price.

Result

Every Renko reversal bar is marked.

Example 2B: Price reversals with a MACD filter

Only long reversals while the MACD line is above zero, and only short reversals while it is below.

Settings and chart

Inflection solver

  • Set up the Inflection solver as in Example 2A.

Threshold solver (the filter)

  • Add a Threshold solver with Indicator set to MACD, and connect it to the Result node.

The Threshold solver alone: Long while the MACD line is above zero, Short while it is below.

Combine them

  • Add an AND node, connect both solvers to it, and connect it to the Result node.

Result

Only the reversals that agree with the MACD filter pass through.

Still stuck? Contact support