exponential_model.cpp
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#include "exponential_model.h"
#include <math.h>
#include <assert.h>
#include "../../poincare/include/poincare_layouts.h"
using namespace Poincare;
namespace Regression {
ExpressionLayout * ExponentialModel::layout() {
static ExpressionLayout * layout = nullptr;
if (layout == nullptr) {
const ExpressionLayout * layoutChildren[] = {
new CharLayout('a', KDText::FontSize::Small),
new CharLayout(Ion::Charset::MiddleDot, KDText::FontSize::Small),
new CharLayout('e', KDText::FontSize::Small),
new VerticalOffsetLayout(
new HorizontalLayout(
new CharLayout('b', KDText::FontSize::Small),
new CharLayout(Ion::Charset::MiddleDot, KDText::FontSize::Small),
new CharLayout('X', KDText::FontSize::Small),
false),
VerticalOffsetLayout::Type::Superscript,
false)
};
layout = new HorizontalLayout(layoutChildren, 4, false);
}
return layout;
}
double ExponentialModel::evaluate(double * modelCoefficients, double x) const {
double a = modelCoefficients[0];
double b = modelCoefficients[1];
return a*exp(b*x);
}
double ExponentialModel::levelSet(double * modelCoefficients, double xMin, double step, double xMax, double y, Poincare::Context * context) {
double a = modelCoefficients[0];
double b = modelCoefficients[1];
if (a == 0 || b == 0 || y/a <= 0) {
return NAN;
}
return log(y/a)/b;
}
double ExponentialModel::partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const {
double a = modelCoefficients[0];
double b = modelCoefficients[1];
if (derivateCoefficientIndex == 0) {
// Derivate: exp(b*x)
return exp(b*x);
}
if (derivateCoefficientIndex == 1) {
// Derivate: a*x*exp(b*x)
return a*x*exp(b*x);
}
assert(false);
return 0.0;
}
}