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<head><title>getNonUnit -- retrieve a previously discovered non-unit</title>
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<div><h1>getNonUnit -- retrieve a previously discovered non-unit</h1>
<div class="single"><h2>Synopsis</h2>
<ul><li><div class="list"><dl class="element"><dt class="heading">Usage: </dt><dd class="value"><div><tt>getNonUnit R</tt></div>
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<li><div class="single">Inputs:<ul><li><span><tt>R</tt>, <span>a <a href="___Ring.html">ring</a></span>, in which division by a non-unit may have been attempted</span></li>
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<li><div class="single">Outputs:<ul><li><span><span>a <a href="___Ring__Element.html">ring element</a></span>, the non-unit, if any, or <a href="_null.html" title="the unique member of the empty class">null</a></span></li>
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<div class="single"><h2>Description</h2>
<div>If a ring has been declared to be a field, using <a href="_to__Field_lp__Ring_rp.html" title="declare that a ring is a field">toField</a> or <a href="_frac.html" title="construct a fraction field">frac</a>, but a nonzero element is found to not be a unit, this routine will return that element, otherwise <a href="_null.html" title="the unique member of the empty class">null</a> is returned.<table class="examples"><tr><td><pre>i1 : A = ZZ/101[a]/(a^2-1);</pre>
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<tr><td><pre>i2 : toField A
o2 = A[]
o2 : PolynomialRing</pre>
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<tr><td><pre>i3 : 1//(a-1)
o3 = 0
o3 : A</pre>
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<tr><td><pre>i4 : getNonUnit A</pre>
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Warning: this function does not work yet for divisions attempted in the course of computing a Gröbner basis or resolution.</div>
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<div class="single"><h2>See also</h2>
<ul><li><span><a href="_to__Field_lp__Ring_rp.html" title="declare that a ring is a field">toField</a> -- declare that a ring is a field</span></li>
<li><span><a href="_frac.html" title="construct a fraction field">frac</a> -- construct a fraction field</span></li>
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