Singular Manual: rootIsolationNoPreprocessing

| #### D.15.30.10 rootIsolationNoPreprocessing Procedure from library `rootisolation.lib` (see rootisolation_lib). Usage: `rootIsolationNoPreprocessing(I, B, eps)`; `I ideal, B list of boxes, eps number`; Assume: `I` is a zero-dimensional radical ideal Return: `(L1, L2)`, where `L1` contains boxes smaller than eps which may contain an element of V(`I`), i.e. a root and `L2` contains boxes which contain exactly one element of V(`I`) Purpose: Given input box(es) `start` we try to find all roots of `I` lying in `start` by computing boxes that contain exactly one root. If `eps` > 0 then boxes that become smaller than `eps` will be returned. Theory: We first check for every box if it contains no roots by interval arithmetic. If this is inconclusive we apply the Newton step which, as outlined in [2] and [3], converges to a root lying in the starting box. If the result of the Newton step is already contained in the interior of the starting box, it contains a unique root. Note: While `rootIsolation` does, `rootIsolationNoPreprocessing` does not check input ideal for necessary conditions. Example:
    LIB "rootisolation.lib";
    ring R = 0,(x,y),dp;
    ideal I = 2x2-xy+2y2-2,2x2-3xy+3y2-2;  // V(I) has four elements
    interval i = bounds(-3/2,3/2);
    box B = list(i, i);
    list result = rootIsolationNoPreprocessing(I, list(B), 1/512);
    size(result[1]);
    ==> 0
    size(result[2]);
    ==> 4
    result;
    ==> [1]:
    ==>    empty list
    ==> [2]:
    ==>    [1]:
    ==>       [-9/16, -15/32] x [-129/128, -127/128]
    ==>    [2]:
    ==>       [15/32, 33/64] x [31/32, 129/128]
    ==>    [3]:
    ==>       [63/64, 33/32] x [-1/256, 1/32]
    ==>    [4]:
    ==>       [-129/128, -63/64] x [-1/256, 1/32]

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