Function evaluateExpression

Fold the legs into one synthetic series.

legs maps each symbol in expr.symbols to its bars. A symbol with no entry, or a bar the primary has and a leg does not, yields no output bar: the series gaps there rather than carrying a stale price forward, because a ratio against yesterday's close is a number that was never true.

const e = parseExpression('NIFTY1!/NSE:RELIANCE');
const bars = evaluateExpression(e, { 'NIFTY1!': a, 'NSE:RELIANCE': b });
chart.addSeries('line').setData(bars);
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volume is deliberately absent from the result. The volume of a ratio is not a quantity anyone traded, and picking one leg's would be arbitrary.