MaplePrimes - comments on Post, i need your help

MaplePrimes - comments on Post, i need your help http://www.mapleprimes.com/posts/37087-I-Need-Your-Help en-us 2026 Maplesoft, A Division of Waterloo Maple Inc. Maplesoft Document System Fri, 12 Jun 2026 14:17:05 GMT Fri, 12 Jun 2026 14:17:05 GMT The latest comments added to the Post, i need your help http://www.mapleprimes.com/images/mapleprimeswhite.jpg MaplePrimes - comments on Post, i need your help http://www.mapleprimes.com/posts/37087-I-Need-Your-Help Probelm with the mathml command http://www.mapleprimes.com/posts/37087-I-Need-Your-Help?ref=Feed:MaplePrimes:i need your help:Comments#comment65045 The following code does not work when $c is $-1 and apparently only in that case. The $disp returns a NULL pointer. Is this a bug or am I doing something wrong? This does not work either if I use the "nosimplify" option. $a1=range(-5,5); $c1=range(-5,5); $c=if(($c1),($c1),1); $a=if(($a1),($a1),1); $n=range(3,5); $q=(($c)*(x)-($a))^($n); $P=maple("expand((($c)*x-($a))^($n))"); $disp=mathml("$q");   The latest comments added to the Post, i need your help 65045 Thu, 02 Jul 2009 20:34:11 Z Pierre Chardaire Pierre Chardaire mathml http://www.mapleprimes.com/posts/37087-I-Need-Your-Help?ref=Feed:MaplePrimes:i need your help:Comments#comment65046 Using MapleTA 4.0, I did not get the NULL pointer error that you described. The mathml does look funny when c=-1 because x gets wrapped in unnecessary parentheses. To avoid this, I suggest you modify your code as follows:   $a1=range(-5,5); $c1=range(-5,5); $c=if(($c1),($c1),1); $a=if(($a1),($a1),1); $n=range(3,5); $q=maple("(($c)*x-($a))^($n)"); $P=maple("expand($q)"); $disp=maple("MathML[ExportPresentation]($q)"); It's never fun to type maple("MathML[ExportPresentation]($foo)") in place of mathml($foo), but the results are always much better.  The latest comments added to the Post, i need your help 65046 Fri, 03 Jul 2009 00:18:45 Z Alex Smith Alex Smith Thanks Alex, I did discover http://www.mapleprimes.com/posts/37087-I-Need-Your-Help?ref=Feed:MaplePrimes:i need your help:Comments#comment65047 Thanks Alex, I did discover that by myself in the end. Pierre. The latest comments added to the Post, i need your help 65047 Thu, 09 Jul 2009 23:45:39 Z Pierre Chardaire Pierre Chardaire derivation the metric tensor http://www.mapleprimes.com/posts/37087-I-Need-Your-Help?ref=Feed:MaplePrimes:i need your help:Comments#comment65048 Hi, I heve to derive the metric tensor by solving a tensor equation like R_{\mu\nu}=0 or G_{\mu\nu}=0 where R is the ricci tensor and G is the Einstein tensor. How can I do this with Msple10? Can maple solve tensor equations to derive the metric tensor? Please help me. Thanks The latest comments added to the Post, i need your help 65048 Sun, 12 Jul 2009 11:39:58 Z Tenor Tenor tensor equations http://www.mapleprimes.com/posts/37087-I-Need-Your-Help?ref=Feed:MaplePrimes:i need your help:Comments#comment65049 The <a href="http://grtensor.phy.queensu.ca/">GRTensor</a> package can help you to derive the field equations. Depending on these equations, Maple may be able to solve them. The latest comments added to the Post, i need your help 65049 Sun, 12 Jul 2009 21:40:17 Z jakubi jakubi ill posed http://www.mapleprimes.com/posts/37087-I-Need-Your-Help?ref=Feed:MaplePrimes:i need your help:Comments#comment65050 Your question seems ill posed. Locally, there are infinitely many metrics for which R_{\mu\nu}=0. Perhaps you want to compute Ricci curvature given the metric, instead of  "solving" for metrics with zero Ricci curvature? The latest comments added to the Post, i need your help 65050 Mon, 13 Jul 2009 04:14:21 Z Alex Smith Alex Smith