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[apps/graph] Use the poincare derivative calculation to compute function

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derivative

Change-Id: I2b4d9b443935ad789e898e253a22f9d2ab652b6a
This commit is contained in:
Émilie Feral
2017-01-10 12:15:08 +01:00
parent afdc1573b2
commit f4a580884b
5 changed files with 7 additions and 9 deletions
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1
apps/constant.cpp
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@@ -2,6 +2,5 @@
constexpr int Constant::FloatBufferSizeInScientificMode;
constexpr int Constant::NumberOfDigitsInMantissaInScientificMode;
constexpr int Constant::NumberOfDigitsInMantissaForDerivativeNumberInScientificMode;
constexpr int Constant::FloatBufferSizeInDecimalMode;
constexpr int Constant::NumberOfDigitsInMantissaInDecimalMode;

1
apps/constant.h
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@@ -5,7 +5,6 @@ class Constant {
public:
constexpr static int FloatBufferSizeInScientificMode = 14;
constexpr static int NumberOfDigitsInMantissaInScientificMode = 7;
constexpr static int NumberOfDigitsInMantissaForDerivativeNumberInScientificMode = 3;
constexpr static int FloatBufferSizeInDecimalMode = 11;
constexpr static int NumberOfDigitsInMantissaInDecimalMode = 4;
};

10
apps/graph/function.cpp
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@@ -83,11 +83,11 @@ float Function::evaluateAtAbscissa(float x, Context * context) const {
}
float Function::approximateDerivative(float x, Context * context) const {
float functionPlus = evaluateAtAbscissa(x + k_epsilon, context);
float functionMinus = evaluateAtAbscissa(x - k_epsilon, context);
float growthRate = (functionPlus - functionMinus)/(2*k_epsilon);
growthRate = roundf(growthRate/k_precision)*k_precision;
return growthRate;
Float abscissa = Float(x);
Expression * args[2] = {m_expression, &abscissa};
Derivative derivative = Derivative();
derivative.setArgument(args, 2, true);
return derivative.approximate(*context);
}
}

2
apps/graph/graph/graph_controller.cpp
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@@ -111,7 +111,7 @@ void GraphController::reloadBannerView() {
buffer[1] = '\'';
App * graphApp = (Graph::App *)app();
float y = f->approximateDerivative(m_cursor.x(), graphApp->localContext());
Float(y).convertFloatToText(buffer+8, Constant::FloatBufferSizeInScientificMode, Constant::NumberOfDigitsInMantissaForDerivativeNumberInScientificMode);
Float(y).convertFloatToText(buffer+8, Constant::FloatBufferSizeInScientificMode, Constant::NumberOfDigitsInMantissaInScientificMode);
m_bannerView.setLegendAtIndex(buffer, 2);
}
m_bannerView.layoutSubviews();

2
apps/graph/values/values_controller.cpp
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@@ -161,7 +161,7 @@ void ValuesController::willDisplayCellAtLocation(TableViewCell * cell, int i, in
float x = m_interval.element(j-1);
App * graphApp = (Graph::App *)app();
if (isDerivativeColumn(i)) {
Float(function->approximateDerivative(x, graphApp->localContext())).convertFloatToText(buffer, Constant::FloatBufferSizeInScientificMode, Constant::NumberOfDigitsInMantissaForDerivativeNumberInScientificMode);
Float(function->approximateDerivative(x, graphApp->localContext())).convertFloatToText(buffer, Constant::FloatBufferSizeInScientificMode, Constant::NumberOfDigitsInMantissaInScientificMode);
} else {
Float(function->evaluateAtAbscissa(x, graphApp->localContext())).convertFloatToText(buffer, Constant::FloatBufferSizeInScientificMode, Constant::NumberOfDigitsInMantissaInScientificMode);
}