Momentum (Mom) - Built-in Indicator Guide

Computes the price change over a specified lookback period, displayed as a blue line.

Overview

Momentum measures the difference between the current source value (typically the closing price) and the value from a user-defined number of bars ago. It is a classic oscillator that shows the speed of price movement without normalizing the result.

A rising momentum line indicates accelerating price movement, while a falling line suggests deceleration. The indicator oscillates around zero: positive values mean the current price is higher than it was N bars ago, negative values mean it is lower.

How it works

1. The indicator accepts two parameters: an integer length (default 10, minimum 1) and a source price (default close).
2. On each bar, it calls Change.new(src, length) which computes src[0] - src[length].
3. The Change algorithm returns a series; the [0] index retrieves the value for the current bar.
4. The result is passed as a scalar to the @plot.line decorator, which draws a solid blue line on the chart.

Mathematical model

Parameters

Code walkthrough

Parameter and source setup

Lines 7-8 of Momentum.indie5:

@param.int('length', default=10, min=1)
@param.source('src', default=source.CLOSE, title='Source')

The length parameter controls the lookback period (default 10 bars). The source parameter lets the user choose which price (close, open, high, low, hl2, etc.) to use as input.

Core computation

Lines 10-11 of Momentum.indie5:

def Main(self, length, src):
    return Change.new(src, length)[0]

The Main function calls Change.new(src, length) which returns a series of differences. Indexing with [0] extracts the current bar’s value. This value is returned as a scalar, which the @plot.line decorator renders as a blue line.

Reading the chart

• A single blue line oscillates around the zero level.
• Positive values indicate the source price is higher than it was length bars ago.
• Negative values indicate the source price is lower than it was length bars ago.
• The magnitude of the line shows the price change over the period.

Implementation notes

• The indicator does not normalize the result, so values depend on the instrument’s price scale.
• On the first length bars, the Change algorithm returns math.nan, so the line starts plotting only after enough bars have elapsed.
• The indicator is stateless and does not repaint; each bar’s value is final once the bar closes.

FAQ

How do I change the lookback period?

Adjust the length parameter in the indicator settings. The default is 10 bars; the minimum is 1.

Can I use a different price source?

Yes. The src parameter accepts any price source, such as open, high, low, close, hl2, hlc3, ohlc4, or hlcc4.

Why does the line start with a flat segment?

The Change algorithm returns math.nan for the first length bars because there is not enough historical data to compute the difference. The line only begins plotting once enough bars have passed.

Full source code

Indie Script v5, the built-in indicator as shipped with TakeProfit. Add it from the indicators menu or copy the code into the platform’s script editor.

# indie:lang_version = 5
from indie import indicator, param, source, plot, color
from indie.algorithms import Change


@indicator('Mom')  # Momentum
@param.int('length', default=10, min=1)
@param.source('src', default=source.CLOSE, title='Source')
@plot.line(color=color.BLUE)
def Main(self, length, src):
    return Change.new(src, length)[0]