float subtrack bug

[ivanova]

ColorBars(480,360)
Subtitle(string(700.0 - 71.7))
Subtitle(string(float(700) - 0.6),y=40)


It gives :

628.299988
699.400024

This is obviously not right, can anyone confirm this?

Using latest avisynth (2.53)

[stickboy]

Looks like normal floating-point behavior to me.

Are you expecting double-precision floats?

(Non-integer values generally cannot be represented exactly in binary. Therefore floating-point calculations inherently are inexact under most circumstances.)

[WarpEnterprises]

ivanova may be right, it is a bit more than only "normal" floating point.

It seems it comes from internal conversions BETWEEN float and double:

double AsFloat() const { _ASSERTE(IsFloat()); return IsInt()?integer:floating_pt; }
...
float floating_pt;


The variable is float and is then returned as double.

[stickboy]

Returning a single-precision float as a double shouldn't introduce additional error (although the conversion seems totally unnecessary), and the values that ivanova gave are consistent with single-precision floating point arithmetic.

I always had assumed that AviSynth used single-precision floats anyway, and I never expected anything beyond that... (I can't find anything in the docs that says anything about it.)