mirror of https://github.com/CGAL/cgal
- fixed some typos in commentes
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@ -958,61 +958,60 @@ ratio_test_2( Tag_false)
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}
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}
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}
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}
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// Idea here: At this point, the goal is to increase \mu_j until
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// Idea here: At this point, the goal is to increase \mu_j until either we
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// either we become optimal (\mu_j=0), or one of the variables in
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// become optimal (\mu_j=0), or one of the variables in x^*_\hat{B} drops
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// x^*_\hat{B} drops down to zero.
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// down to zero.
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//
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//
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// Technically, we do this as follows here. Eq. (2.11) in Sven's
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// Technically, we do this as follows here. Eq. (2.11) in Sven's thesis
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// thesis holds, and by multlying it by $M_\hat{B}^{-1}$ we obtain
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// holds, and by multlying it by $M_\hat{B}^{-1}$ we obtain an equation
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// an equation for \lambda and x^*_\hat{B}. The interesting
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// for \lambda and x^*_\hat{B}. The interesting equation (the one for
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// equation (the one for x^*_\hat{B}) looks more or less as
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// x^*_\hat{B}) looks more or less as follows:
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// follows:
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//
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//
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// x(mu_j) = x(0) + mu_j q_it (1)
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// x(mu_j) = x(0) + mu_j q_it (1)
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//
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//
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// where q_it is the vector from (2.12). In paritcular, for
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// where q_it is the vector from (2.12). In paritcular, for
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// mu_j=mu_j(t_1) (i.e., if we plug the value of mu_j at the
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// mu_j=mu_j(t_1) (i.e., if we plug the value of mu_j at the beginning of
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// beginning of this ratio step 2 into (1)) we have
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// this ratio step 2 into (1)) we have
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//
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//
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// x(mu_j(t_1)) = x(0) + mu_j(t_1) q_it (2)
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// x(mu_j(t_1)) = x(0) + mu_j(t_1) q_it (2)
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//
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//
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// where x(mu_j(t_1)) is the current solution of the solver at
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// where x(mu_j(t_1)) is the current solution of the solver at this point
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// this point (i.e., at the beginning of ratio step 2).
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// (i.e., at the beginning of ratio step 2).
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//
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//
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// By subtracting (2) from (1) we can thus eliminate the "unkown"
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// By subtracting (2) from (1) we can thus eliminate the "unkown" x(0)
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// x(0) (which is cheaper than computing it!):
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// (which is cheaper than computing it):
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//
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//
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// x(mu_j) = x(mu_j(t_1)) + (mu_j-mu_j(t_1)) q_it
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// x(mu_j) = x(mu_j(t_1)) + (mu_j-mu_j(t_1)) q_it
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// ----------------
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// ----------------
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// := delta
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// := delta
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//
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//
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// In order to compute for each variable x_k in \hat{B} the value
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// In order to compute for each variable x_k in \hat{B} the value of mu_j
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// of mu_j for which x_k(mu_j) = 0, we thus evaluate
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// for which x_k(mu_j) = 0, we thus evaluate
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//
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//
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// x(mu_j(t_1))
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// x(mu_j(t_1))_k
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// delta_k:= - ------------
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// delta_k:= - --------------
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// q_it
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// q_it_k
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//
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//
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// The first variable in \hat{B} that hits zero "in the future" is
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// The first variable in \hat{B} that hits zero "in the future" is then
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// then the one whose delta_k equals
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// the one whose delta_k equals
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//
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//
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// delta_min:= min {delta_k | k in \hat{B} and (q_it)_k < 0 }
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// delta_min:= min {delta_k | k in \hat{B} and (q_it)_k < 0 }
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//
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//
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// Below we are thus going to compute this minimum. Once we have
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// Below we are thus going to compute this minimum. Once we have
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// delta_min, we need to check whether we get optimal BEFORE a
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// delta_min, we need to check whether we get optimal BEFORE a variable
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// variable drwops to zero. As delta = mu_j - mu_j(t_1), the
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// drops to zero. As delta = mu_j - mu_j(t_1), the latter is precisely
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// latter is precisely the case if delta_min >= -mu_j(t_1).
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// the case if delta_min >= -mu_j(t_1).
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//
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//
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// (Note: please forget the crap identitiy between (2.11) and
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// (Note: please forget the crap identitiy between (2.11) and (2.12); the
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// (2.12); the notation is misleading.)
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// notation is misleading.)
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// By definition delta_min >= 0, such that initializing
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// fw: By definition delta_min >= 0, such that initializing
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// delta_min with -mu_j(t_1) has the desired effect that a basic variable
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// delta_min with -mu_j(t_1) has the desired effect that a basic variable
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// is leaving only if 0 <= delta_min < -mu_j(t_1).
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// is leaving only if 0 <= delta_min < -mu_j(t_1).
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//
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// The only initialization of delta_min as fraction x_i/q_i that works is
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// The only initialization of delta_min as fraction x_i/q_i that works is
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// x_i=mu_j(t_1); q_i=-1; (see below).
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// x_i=mu_j(t_1); q_i=-1; (see below).
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//
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// Since mu_j(t_1) has been computed in ratio test step 1 we can
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// Since mu_j(t_1) has been computed in ratio test step 1 we can
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// reuse it.
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// reuse it.
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