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fix(foc utils): restore the FLT_MIN guard in _atan2() #583

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fix(foc utils): restore the FLT_MIN guard in _atan2() #583

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fix(foc utils): restore the FLT_MIN guard in _atan2()
stijncarelsbergh Oct 7, 2026
f43a780
refactor(foc utils): use the comparison chain suggested in review, ke…
stijncarelsbergh Oct 10, 2026
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10 changes: 8 additions & 2 deletions src/common/foc_utils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -55,8 +55,14 @@ __attribute__((weak)) float _atan2(float y, float x) {
// a := min (|x|, |y|) / max (|x|, |y|)
float abs_y = fabsf(y);
float abs_x = fabsf(x);
// inject FLT_MIN in denominator to avoid division by zero
float a = min(abs_x, abs_y) / (max(abs_x, abs_y));
// the single comparison chain avoids the division by zero without an epsilon in the
// denominator; the |x| == |y| case still needs to divide (a == 1), only the
// degenerate (0,0) input returns early - atan2(0,0) is 0
float a;
if (abs_x < abs_y) a = abs_x / abs_y;
else if (abs_x > abs_y) a = abs_y / abs_x;
else if (abs_x == 0.0f) return 0.0f;
else a = 1.0f;
// s := a * a
float s = a * a;
// r := ((-0.0464964749 * s + 0.15931422) * s - 0.327622764) * s * a + a
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