why the (sub) behavior like this?

[dexter]

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(sub 1.9 0.2) will work as I thought

but (sub 20000.9 20000.2) will not return 0.7 insead of
0.700000000000728



why not just return 0.7 ??



my newlisp is 10.6.0

[rrq]

Maybe it has something to do with https://en.wikipedia.org/wiki/Single-precision_floating-point_format">//https://en.wikipedia.org/wiki/Single-precision_floating-point_format

Try

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(format "%.30f" 20000.9)

[dexter]

thanks



in the end ,I (mul) the number to be an integer,than I can deal the number with (-)