That must be a reference to tolerant comparison, but the way it's written is bizarre. Comparisons in APL are (optionally: you can turn it off) subject to tolerance, meaning that numbers with a small enough difference are treated as equal by comparison or search functions. There are probably better resources but I describe it at [0].
However, Dyalog just uses IEEE doubles (with an error in place of infinities or NaNs; also you can configure to use higher-precision decimal floats), no different from JavaScript. The result of, say, 0.1+0.2, is not the same as 0.3, it's just equal under tolerant comparison.
However, Dyalog just uses IEEE doubles (with an error in place of infinities or NaNs; also you can configure to use higher-precision decimal floats), no different from JavaScript. The result of, say, 0.1+0.2, is not the same as 0.3, it's just equal under tolerant comparison.
[0] https://www.dyalog.com/blog/2018/11/tolerated-comparison-par...