[GitHub] mlampert commented on a change in pull request #947: Refactor/easing library
mlampert commented on a change in pull request #947: Refactor/easing library
URL: https://github.com/apache/mynewt-core/pull/947#discussion_r178368672
##
File path: util/easing/src/easing.c
##
@@ -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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[GitHub] mlampert commented on a change in pull request #947: Refactor/easing library
mlampert commented on a change in pull request #947: Refactor/easing library
URL: https://github.com/apache/mynewt-core/pull/947#discussion_r178368672
##
File path: util/easing/src/easing.c
##
@@ -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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[GitHub] mlampert commented on a change in pull request #947: Refactor/easing library
mlampert commented on a change in pull request #947: Refactor/easing library
URL: https://github.com/apache/mynewt-core/pull/947#discussion_r178368006
##
File path: util/easing/src/easing.c
##
@@ -43,12 +43,12 @@ static inline float exponential_out(float step, float
max_steps, float max_val)
{
return (step == max_steps) ?
max_val :
-max_val - pow(max_val, 1.0 - (float)step/max_steps);
+max_val - pow(max_val, 1.0f - (float)step/max_steps);
Review comment:
I'm not sure why the original implementation had that cast there, it was
promoted to a `double` anyway. I presume that early on `step` and `max_step`
were integer values and it was a remnant of refactoring. I can certainly clean
those up.
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[GitHub] mlampert commented on a change in pull request #947: Refactor/easing library
mlampert commented on a change in pull request #947: Refactor/easing library
URL: https://github.com/apache/mynewt-core/pull/947#discussion_r178365725
##
File path: util/easing/src/easing.c
##
@@ -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);
}
static inline float cubic_out(float step, float max_steps, float max_val)
{
- float ratio = step / (max_steps - 1.0);
+ float ratio = step / (max_steps - 1.0f);
- return max_val * (pow(ratio, 3) + 1);
+ return max_val * ((ratio * ratio * ratio) + 1);
}
static inline float cubic_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 * pow(ratio, 3);
+ return max_val / 2 * (ratio * ratio * ratio);
- return max_val / 2 * (pow(ratio - 2, 3) + 2);
+ratio -= 2;
+ return max_val / 2 * ((ratio * ratio * ratio) + 2);
}
/* Quartic */
static inline float quartic_in(float step, float max_steps, float max_val)
{
float ratio = step / max_steps;
- return max_val * pow(ratio, 4);
+ return max_val * (ratio * ratio * ratio * ratio);
}
static inline float quartic_out(float step, float max_steps, float max_val)
{
- float ratio = (step / max_steps) - 1.0;
+ float ratio = (step / max_steps) - 1.0f;
- return max_val + max_val * pow(ratio, 5);
+ return max_val + max_val * (ratio * ratio * ratio * ratio * ratio);
}
static inline float quartic_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 * pow(ratio, 4);
+ return max_val / 2 * (ratio * ratio * ratio * ratio);
- return max_val + max_val / 2 * pow(ratio -2, 5);
+ratio -= 2;
Review comment:
the weird identation comes from the original source code having tab
characters in some places and github uses tabstop=8. I didn't clean up the tabs
because it introduces a lot of noise into the code review but can certainly do
that.
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