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Fixing newton again #66

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merged 1 commit into from
Nov 17, 2023
Merged

Fixing newton again #66

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2 changes: 1 addition & 1 deletion src/scion/math/SeriesBase/src/roots.hpp
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Test if the f(X) at that value is already zero so you avoid to loop through newton method.

Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ std::vector< X > roots( const Y& a = Y( 0. ) ) const {

if ( isCloseToZero( value.imag() ) ) {

roots.emplace_back( derivative( value.real() ) != X( 0. )
roots.emplace_back( !isCloseToZero( derivative( value.real() ) )
? newton( value.real(), functor, derivative )
: value.real() );
}
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6 changes: 5 additions & 1 deletion src/scion/math/newton.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -35,11 +35,15 @@ X newton( X estimate, Functor&& functor, Derivative&& derivative,
int iterations = 5 ) noexcept {

X root = estimate - functor( estimate ) / derivative( estimate );
while ( ( ! isClose( root, estimate ) ) || ( iterations != 0 ) ) {
while ( ! isClose( root, estimate ) ) {

std::swap( estimate, root );
root = estimate - functor( estimate ) / derivative( estimate );
--iterations;
if ( iterations == 0 ) {

break;
}
}
return root;
}
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