How was it output
float2 A = 1.0 / ReShade::ScreenSize;
float2 B = ReShade::PixelSize;
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My case (this is lower than FLT_EPSILON)
const float2 _50 = float2(0.00099206, 0.00131406);
float2 A;
A = _50;
const float2 _52 = float2(0.00099200, 0.00131400);
float2 B;
B = _52;
[Edit]
I guess out of precision was trimmed at float2(BUFFER_RCP_WIDTH, BUFFER_RCP_HEIGHT).
float precision is about 6 digits.
202px
A = 0.00495049 ... 202.000206
B = 0.00495000 ... 202.020202
3840px
A = 0.00026042 ... 3839.95
B = 0.00026000 ... 3846.15