ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Tue, 19 Feb 2013 18:06:26 +0100Equalities/Inequalities in Polyhedron()https://ask.sagemath.org/question/9805/equalitiesinequalities-in-polyhedron/Hi,
Anyone can please tell me that what equalities/inequalities in polyhedron(eqns = [()]) represent. e.g. for the following expression
P = Polyhedron(eqns=[(0,0,1,0)])
plane2.Hrepresentation()
The result is (An equation (0, 1, 0) x + 0 == 0,). Does it mean x2 = 0 plane in 3D?
Similarly for
plane3 = Polyhedron(eqns=[(1,0,0,-1)])
plane3.Hrepresentation()
the result is (An equation (0, 0, 1) x - 1 == 0,). Does it mean x3 = 1 in 3D.
If not so, how do we interpret it?
ThanksTue, 19 Feb 2013 00:44:44 +0100https://ask.sagemath.org/question/9805/equalitiesinequalities-in-polyhedron/Answer by twch for <p>Hi,</p>
<p>Anyone can please tell me that what equalities/inequalities in polyhedron(eqns = [()]) represent. e.g. for the following expression </p>
<p>P = Polyhedron(eqns=[(0,0,1,0)])
plane2.Hrepresentation()</p>
<p>The result is (An equation (0, 1, 0) x + 0 == 0,). Does it mean x2 = 0 plane in 3D?</p>
<p>Similarly for </p>
<p>plane3 = Polyhedron(eqns=[(1,0,0,-1)])
plane3.Hrepresentation()</p>
<p>the result is (An equation (0, 0, 1) x - 1 == 0,). Does it mean x3 = 1 in 3D. </p>
<p>If not so, how do we interpret it?</p>
<p>Thanks</p>
https://ask.sagemath.org/question/9805/equalitiesinequalities-in-polyhedron/?answer=14561#post-id-14561Yes you are completely right
eqns=[(a,b,c,d)]
means exactly
a+b*x_1+c*x_2+d*x_3=0
The same is true for inequalities where = is replaced by ">=".
You can also plot the corresponding surface in R^3 with
plane3.show()
which should make clear who to interpret the equation. Tue, 19 Feb 2013 16:38:14 +0100https://ask.sagemath.org/question/9805/equalitiesinequalities-in-polyhedron/?answer=14561#post-id-14561Comment by assadabbasi for <p>Yes you are completely right </p>
<pre><code>eqns=[(a,b,c,d)]
</code></pre>
<p>means exactly </p>
<pre><code>a+b*x_1+c*x_2+d*x_3=0
</code></pre>
<p>The same is true for inequalities where = is replaced by ">=".</p>
<p>You can also plot the corresponding surface in R^3 with </p>
<pre><code>plane3.show()
</code></pre>
<p>which should make clear who to interpret the equation. </p>
https://ask.sagemath.org/question/9805/equalitiesinequalities-in-polyhedron/?comment=18212#post-id-18212Thanks for the clarificationTue, 19 Feb 2013 18:06:26 +0100https://ask.sagemath.org/question/9805/equalitiesinequalities-in-polyhedron/?comment=18212#post-id-18212