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Spartan322Spartan322
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Merge pull request #148 from NickUfer/sigmoid_funcs
Add sigmoid(), sigmoid_approx(), sigmoid_affine() and sigmoid_affine_approx() functions
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‎core/math/math_funcs.h‎

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@@ -759,6 +759,20 @@ class Math {
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}
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return p_target;
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}
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static _ALWAYS_INLINE_ double sigmoid_affine(double p_x, double p_amplitude, double p_y_translation) {
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return p_amplitude / (1.0 + ::exp(-p_x)) + p_y_translation;
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}
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static _ALWAYS_INLINE_ float sigmoid_affine(float p_x, float p_amplitude, float p_y_translation) {
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return p_amplitude / (1.0f + expf(-p_x)) + p_y_translation;
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}
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static _ALWAYS_INLINE_ double sigmoid_affine_approx(double p_x, double p_amplitude, double p_y_translation) {
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return p_amplitude * (0.5 + p_x / (4.0 + fabs(p_x))) + p_y_translation;
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}
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static _ALWAYS_INLINE_ float sigmoid_affine_approx(float p_x, float p_amplitude, float p_y_translation) {
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return p_amplitude * (0.5f + p_x / (4.0f + fabsf(p_x))) + p_y_translation;
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}
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};
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#endif // MATH_FUNCS_H

‎core/variant/variant_utility.cpp‎

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@@ -641,6 +641,22 @@ double VariantUtilityFunctions::pingpong(double value, double length) {
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return Math::pingpong(value, length);
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}
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double VariantUtilityFunctions::sigmoid(double x) {
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return Math::sigmoid_affine(x, 1.0, 0.0);
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}
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double VariantUtilityFunctions::sigmoid_approx(double x) {
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return Math::sigmoid_affine_approx(x, 1.0, 0.0);
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}
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double VariantUtilityFunctions::sigmoid_affine(double x, double amplitude, double y_translation) {
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return Math::sigmoid_affine(x, amplitude, y_translation);
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}
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double VariantUtilityFunctions::sigmoid_affine_approx(double x, double amplitude, double y_translation) {
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return Math::sigmoid_affine_approx(x, amplitude, y_translation);
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}
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Variant VariantUtilityFunctions::max(const Variant **p_args, int p_argcount, Callable::CallError &r_error) {
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if (p_argcount < 2) {
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r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
@@ -1809,6 +1825,11 @@ void Variant::_register_variant_utility_functions() {
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FUNCBINDR(nearest_po2, sarray("value"), Variant::UTILITY_FUNC_TYPE_MATH);
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FUNCBINDR(pingpong, sarray("value", "length"), Variant::UTILITY_FUNC_TYPE_MATH);
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FUNCBINDR(sigmoid, sarray("x"), Variant::UTILITY_FUNC_TYPE_MATH);
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FUNCBINDR(sigmoid_approx, sarray("x"), Variant::UTILITY_FUNC_TYPE_MATH);
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FUNCBINDR(sigmoid_affine, sarray("x", "amplitude", "y_translation"), Variant::UTILITY_FUNC_TYPE_MATH);
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FUNCBINDR(sigmoid_affine_approx, sarray("x", "amplitude", "y_translation"), Variant::UTILITY_FUNC_TYPE_MATH);
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// Random
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FUNCBIND(randomize, sarray(), Variant::UTILITY_FUNC_TYPE_RANDOM);

‎core/variant/variant_utility.h‎

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@@ -117,6 +117,10 @@ struct VariantUtilityFunctions {
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static double clampf(double x, double min, double max);
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static int64_t clampi(int64_t x, int64_t min, int64_t max);
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static int64_t nearest_po2(int64_t x);
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static double sigmoid(double x);
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static double sigmoid_approx(double x);
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static double sigmoid_affine(double x, double amplitude, double y_translation);
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static double sigmoid_affine_approx(double x, double amplitude, double y_translation);
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// Random
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static void randomize();
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static int64_t randi();

‎doc/classes/@GlobalScope.xml‎

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@@ -1185,6 +1185,84 @@
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[/codeblocks]
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</description>
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</method>
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<method name="sigmoid">
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<return type="float" />
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<param index="0" name="x" type="float" />
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<description>
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Computes the sigmoid for [param x], which maps the input value into the range (0, 1).
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The sigmoid function is defined as:
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[codeblock]
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sigmoid(x) = 1 / (1 + exp(-x))
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[/codeblock]
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This is the most accurate implementation of the sigmoid.
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[codeblock]
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var result = sigmoid(0.0) # result is 0.5
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var result = sigmoid(1.0) # result is approximately 0.7310
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var result = sigmoid(-1.0) # result is approximately 0.2689
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var result = sigmoid(5.0) # result is approximately 0.9933
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[/codeblock]
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[b]Note:[/b] For faster but less accurate approximation, see [method sigmoid_approx].
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</description>
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</method>
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<method name="sigmoid_affine">
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<return type="float" />
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<param index="0" name="x" type="float" />
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<param index="1" name="amplitude" type="float" />
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<param index="2" name="y_translation" type="float" />
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<description>
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Computes an affine-transformed sigmoid for [param x], which allows scaling by [param amplitude] and translation by [param y_translation].
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The affine sigmoid function is defined as:
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[codeblock]
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sigmoid_affine(x, amplitude, y_translation) = (amplitude / (1 + exp(-x))) + y_translation
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[/codeblock]
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This function modifies the standard sigmoid by introducing scaling and vertical translation.
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[codeblock]
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var result = sigmoid_affine(0.0, 1.0, 0.0) # result is 0.5
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var result = sigmoid_affine(1.0, 2.0, -1.0) # result is approximately 0.4621
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var result = sigmoid_affine(-1.0, 3.0, 2.0) # result is approximately 2.8068
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var result = sigmoid_affine(1.0, 2.0, 2.5) # result is approximately 3.9621
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[/codeblock]
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[b]Note:[/b] This is a more accurate but computationally heavier version of the affine sigmoid. For faster approximations, see [method sigmoid_affine_approx].
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</description>
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</method>
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<method name="sigmoid_affine_approx">
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<return type="float" />
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<param index="0" name="x" type="float" />
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<param index="1" name="amplitude" type="float" />
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<param index="2" name="y_translation" type="float" />
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<description>
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Computes an approximation of the affine-transformed sigmoid function for [param x], allowing scaling by [param amplitude] and translation by [param y_translation].
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The approximation function is defined as:
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[codeblock]
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affine_sigmoid_approx(x, amplitude, y_translation) = amplitude * (0.5 + (x / (4 + abs(x)))) + y_translation
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[/codeblock]
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This function approximates the affine sigmoid, offering faster computation at the cost of some precision. It is useful in performance-sensitive environments where both transformation and speed are needed.
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[codeblock]
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var result = sigmoid_affine_approx(0.0, 1.0, 0.0) # result is 0.5
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var result = sigmoid_affine_approx(2.0, 2.0, 1.0) # result is approximately 2.6667
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var result = sigmoid_affine_approx(-1.0, 3.0, 0.5) # result is 1.4
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var result = sigmoid_affine_approx(1.0, 2.0, 2.5) # result is 3.9
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[/codeblock]
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</description>
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</method>
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<method name="sigmoid_approx">
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<return type="float" />
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<param index="0" name="x" type="float" />
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<description>
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Computes an approximation of the sigmoid function for [param x], which maps the input value into the range (0, 1).
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The approximation function is defined as:
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[codeblock]
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sigmoid_approx(x) = 0.5 + (x / (4 + abs(x)))
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[/codeblock]
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This function is faster than the standard [method sigmoid], especially useful in performance-sensitive environments where a balance between accuracy and speed is desired.
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[codeblock]
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var result = sigmoid_approx(0.0) # result is 0.5
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var result = sigmoid_approx(2.0) # result is approximately 0.8333
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var result = sigmoid_approx(-1.0) # result is 0.3
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var result = sigmoid_approx(5.0) # result is approximately 1.0555
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[/codeblock]
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</description>
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</method>
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<method name="sign">
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<return type="Variant" />
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<param index="0" name="x" type="Variant" />

‎tests/core/math/test_math_funcs.h‎

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@@ -641,6 +641,20 @@ TEST_CASE_TEMPLATE("[Math] bezier_interpolate", T, float, double) {
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CHECK(Math::bezier_interpolate((T)0.0, (T)0.2, (T)0.8, (T)1.0, (T)1.0) == doctest::Approx((T)1.0));
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}
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TEST_CASE_TEMPLATE("[Math] sigmoid_affine", T, float, double) {
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CHECK(Math::sigmoid_affine((T)0.0, (T)1.0, (T)0.0) == doctest::Approx((T)0.5));
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CHECK(Math::sigmoid_affine((T)1.0, (T)2.0, (T)-1.0) == doctest::Approx((T)0.4621));
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CHECK(Math::sigmoid_affine((T)-1.0, (T)3.0, (T)2.0) == doctest::Approx((T)2.8068));
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CHECK(Math::sigmoid_affine((T)1.0, (T)2.0, (T)2.5) == doctest::Approx((T)3.9621));
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}
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TEST_CASE_TEMPLATE("[Math] sigmoid_affine_approx", T, float, double) {
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CHECK(Math::sigmoid_affine_approx((T)0.0, (T)1.0, (T)0.0) == doctest::Approx((T)0.5));
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CHECK(Math::sigmoid_affine_approx((T)2.0, (T)2.0, (T)1.0) == doctest::Approx((T)2.6667));
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CHECK(Math::sigmoid_affine_approx((T)-1.0, (T)3.0, (T)0.5) == doctest::Approx((T)1.4));
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CHECK(Math::sigmoid_affine_approx((T)1.0, (T)2.0, (T)2.5) == doctest::Approx((T)3.9));
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}
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} // namespace TestMath
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#endif // TEST_MATH_FUNCS_H

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