permute_coefficient.cpp
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#include <poincare/permute_coefficient.h>
#include <poincare/undefined.h>
#include <poincare/rational.h>
extern "C" {
#include <assert.h>
}
#include <cmath>
namespace Poincare {
Expression::Type PermuteCoefficient::type() const {
return Type::PermuteCoefficient;
}
Expression * PermuteCoefficient::clone() const {
PermuteCoefficient * b = new PermuteCoefficient(m_operands, true);
return b;
}
Expression * PermuteCoefficient::shallowReduce(Context& context, AngleUnit angleUnit) {
Expression * e = Expression::shallowReduce(context, angleUnit);
if (e != this) {
return e;
}
Expression * op0 = editableOperand(0);
Expression * op1 = editableOperand(1);
#if MATRIX_EXACT_REDUCING
if (op0->type() == Type::Matrix || op1->type() == Type::Matrix) {
return replaceWith(new Undefined(), true);
}
#endif
if (op0->type() == Type::Rational) {
Rational * r0 = static_cast<Rational *>(op0);
if (!r0->denominator().isOne() || r0->numerator().isNegative()) {
return replaceWith(new Undefined(), true);
}
}
if (op1->type() == Type::Rational) {
Rational * r1 = static_cast<Rational *>(op1);
if (!r1->denominator().isOne() || r1->numerator().isNegative()) {
return replaceWith(new Undefined(), true);
}
}
if (op0->type() != Type::Rational || op1->type() != Type::Rational) {
return this;
}
Rational * r0 = static_cast<Rational *>(op0);
Rational * r1 = static_cast<Rational *>(op1);
Integer n = r0->numerator();
Integer k = r1->numerator();
if (n.isLowerThan(k)) {
return replaceWith(new Rational(0), true);
}
/* if n is too big, we do not reduce to avoid too long computation.
* The permute coefficient will be evaluate approximatively later */
if (Integer(k_maxNValue).isLowerThan(n)) {
return this;
}
Integer result(1);
int clippedK = k.extractedInt(); // Authorized because k < n < k_maxNValue
for (int i = 0; i < clippedK; i++) {
Integer factor = Integer::Subtraction(n, Integer(i));
result = Integer::Multiplication(result, factor);
}
return replaceWith(new Rational(result), true);
}
template<typename T>
Complex<T> * PermuteCoefficient::templatedApproximate(Context& context, AngleUnit angleUnit) const { Evaluation<T> * nInput = operand(0)->privateApproximate(T(), context, angleUnit);
Evaluation<T> * kInput = operand(1)->privateApproximate(T(), context, angleUnit);
T n = nInput->toScalar();
T k = kInput->toScalar();
delete nInput;
delete kInput;
if (std::isnan(n) || std::isnan(k) || n != std::round(n) || k != std::round(k) || n < 0.0f || k < 0.0f) {
return new Complex<T>(Complex<T>::Undefined());
}
if (k > n) {
return new Complex<T>(0);
}
T result = 1;
for (int i = (int)n-(int)k+1; i <= (int)n; i++) {
result *= i;
if (std::isinf(result) || std::isnan(result)) {
return new Complex<T>(result);
}
}
return new Complex<T>(std::round(result));
}
}