mlampert commented on a change in pull request #947: Refactor/easing library
URL: https://github.com/apache/mynewt-core/pull/947#discussion_r178368672
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File path: util/easing/src/easing.c
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@@ -69,125 +69,128 @@ static inline float quadratic_in(float step, float
max_steps, float max_val)
{
float ratio = step / max_steps;
- return max_val * pow(ratio, 2);
+ return max_val * (ratio * ratio);
}
static inline float quadratic_out(float step, float max_steps, float max_val)
{
float ratio = step / max_steps;
- return -max_val * ratio * (ratio - 2.0);
+ return -max_val * ratio * (ratio - 2.0f);
}
static inline float quadratic_io(float step, float max_steps, float max_val)
{
- float ratio = step / (max_steps / 2.0);
+ float ratio = step / (max_steps / 2.0f);
if (ratio < 1)
- return max_val / 2.0 * pow(ratio, 2);
+ return max_val / 2.0f * (ratio * ratio);
- ratio = (step - (max_steps/2.0)) / (max_steps/2.0);
- return (max_val / 2.0) - (max_val / 2.0) * ratio * (ratio - 2.0);
+ ratio = (step - (max_steps/2.0f)) / (max_steps/2.0f);
+ return (max_val / 2.0f) - (max_val / 2.0f) * ratio * (ratio - 2.0f);
}
/* Cubic */
static inline float cubic_in(float step, float max_steps, float max_val)
{
float ratio = step / max_steps;
- return max_val * pow(ratio, 3);
+ return max_val * (ratio * ratio * ratio);
Review comment:
Understood - but I cannot answer that question without a reference. The
interface does not suggest that there is `double` precision involved, it's all
based on `float` so as a user that's as much as I can expect. In order to
answer the question if this refactoring falsifies the result we would need a
definition as to what level of deviation is acceptable.
In addition none of the computations uses accumulation which is where
`float`'s really start bleeding, all values are monotonically increasing or
decreasing and the result is converted to a float. So if the initial value and
the result fits into a `float` then every intermediary value will also fit.
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