```Date: Feb 2, 2013 1:46 PM
Author: Hugo
Subject: Matrix is singular and is not supposed to be.

Hello, I am trying to obtain deflection results on a beam made with shell elementsI wrote a MATLAB code. The problem is that kk is a matrix with 3000*3000 full of zeros (itÂ´s a singular matrix), and it is not supposed to be.The code runs well until I call the function feasmbl1.m, which is shown nextfunction [kk]=feasmbl1(kk,k,index)%----------------------------------------------------------%  Purpose:%     Assembly of element matrices into the system matrix%%  Synopsis:%     [kk]=feasmbl1(kk,k,index)%%  Variable Description:%     kk - system matrix%     k  - element matri%     index - d.o.f. vector associated with an element%-----------------------------------------------------------  edof = length(index); for i=1:edof   ii=index(i);     for j=1:edof       jj=index(j);         kk(ii,jj)=kk(ii,jj)+k(i,j);     end end The values of the scalars used in the function are:edof=24ii=192jj=192my index is calculated by a previous function, and has the following values:index =     1     2     3     4     5     6    13    14    15    16    17    18   241   242   243   244   245   246   187   188   189   190   191   192My k is a matrix and is equal to:kt =   1.0e+09 *  Columns 1 through 9    0.0099   -0.0049   -0.0476    0.0012   -0.0063    0.0002    0.0310   -0.0006   -0.1653    0.0106   -0.0061   -0.0719    0.0017   -0.0092    0.0004    0.0414   -0.0008   -0.2408    0.0379   -0.0197   -0.1708    0.0042   -0.0227    0.0006    0.1160   -0.0025   -0.5958   -0.0011    0.0008    0.0036   -0.0001    0.0005   -0.0000   -0.0032    0.0001    0.0130    0.0051   -0.0026   -0.0229    0.0006   -0.0031    0.0001    0.0156   -0.0003   -0.0800    0.0013   -0.0024    0.0055   -0.0001    0.0006   -0.0000    0.0021   -0.0003    0.0168    0.0344   -0.0170   -0.1655    0.0041   -0.0219    0.0006    0.1073   -0.0021   -0.5748   -0.0262    0.0558   -0.1797    0.0040   -0.0214    0.0007   -0.0284    0.0070   -0.5619    0.1332   -0.0691   -0.6005    0.0149   -0.0800    0.0022    0.4076   -0.0086   -2.0945   -0.0011    0.0008    0.0036   -0.0001    0.0005   -0.0000   -0.0032    0.0001    0.0130    0.0051   -0.0026   -0.0229    0.0006   -0.0031    0.0001    0.0156   -0.0003   -0.0800    0.0013   -0.0024    0.0055   -0.0001    0.0006   -0.0000    0.0021   -0.0003    0.0168   -0.0099    0.0049    0.0476   -0.0012    0.0063   -0.0002   -0.0310    0.0006    0.1653   -0.0106    0.0061    0.0719   -0.0017    0.0092   -0.0004   -0.0414    0.0008    0.2408   -0.0379    0.0197    0.1708   -0.0042    0.0227   -0.0006   -0.1160    0.0025    0.5958   -0.0011    0.0008    0.0036   -0.0001    0.0005   -0.0000   -0.0032    0.0001    0.0130    0.0051   -0.0026   -0.0229    0.0006   -0.0031    0.0001    0.0156   -0.0003   -0.0800    0.0013   -0.0024    0.0055   -0.0001    0.0006   -0.0000    0.0021   -0.0003    0.0168   -0.0344    0.0170    0.1655   -0.0041    0.0219   -0.0006   -0.1073    0.0021    0.5748    0.0262   -0.0558    0.1797   -0.0040    0.0214   -0.0007    0.0284   -0.0070    0.5619   -0.1332    0.0691    0.6005   -0.0149    0.0800   -0.0022   -0.4076    0.0086    2.0945   -0.0011    0.0008    0.0036   -0.0001    0.0005   -0.0000   -0.0032    0.0001    0.0130    0.0051   -0.0026   -0.0229    0.0006   -0.0031    0.0001    0.0156   -0.0003   -0.0800    0.0013   -0.0024    0.0055   -0.0001    0.0006   -0.0000    0.0021   -0.0003    0.0168  Columns 10 through 18    0.0012   -0.0063    0.0002   -0.0099    0.0049    0.0476    0.0012   -0.0063    0.0002    0.0017   -0.0092    0.0004   -0.0106    0.0061    0.0719    0.0017   -0.0092    0.0004    0.0042   -0.0227    0.0006   -0.0379    0.0197    0.1708    0.0042   -0.0227    0.0006   -0.0001    0.0005   -0.0000    0.0011   -0.0008   -0.0036   -0.0001    0.0005   -0.0000    0.0006   -0.0031    0.0001   -0.0051    0.0026    0.0229    0.0006   -0.0031    0.0001   -0.0001    0.0006   -0.0000   -0.0013    0.0024   -0.0055   -0.0001    0.0006   -0.0000    0.0041   -0.0219    0.0006   -0.0344    0.0170    0.1655    0.0041   -0.0219    0.0006    0.0040   -0.0214    0.0007    0.0262   -0.0558    0.1797    0.0040   -0.0214    0.0007    0.0149   -0.0800    0.0022   -0.1332    0.0691    0.6005    0.0149   -0.0800    0.0022   -0.0001    0.0005   -0.0000    0.0011   -0.0008   -0.0036   -0.0001    0.0005   -0.0000    0.0006   -0.0031    0.0001   -0.0051    0.0026    0.0229    0.0006   -0.0031    0.0001   -0.0001    0.0006   -0.0000   -0.0013    0.0024   -0.0055   -0.0001    0.0006   -0.0000   -0.0012    0.0063   -0.0002    0.0099   -0.0049   -0.0476   -0.0012    0.0063   -0.0002   -0.0017    0.0092   -0.0004    0.0106   -0.0061   -0.0719   -0.0017    0.0092   -0.0004   -0.0042    0.0227   -0.0006    0.0379   -0.0197   -0.1708   -0.0042    0.0227   -0.0006   -0.0001    0.0005   -0.0000    0.0011   -0.0008   -0.0036   -0.0001    0.0005   -0.0000    0.0006   -0.0031    0.0001   -0.0051    0.0026    0.0229    0.0006   -0.0031    0.0001   -0.0001    0.0006   -0.0000   -0.0013    0.0024   -0.0055   -0.0001    0.0006   -0.0000   -0.0041    0.0219   -0.0006    0.0344   -0.0170   -0.1655   -0.0041    0.0219   -0.0006   -0.0040    0.0214   -0.0007   -0.0262    0.0558   -0.1797   -0.0040    0.0214   -0.0007   -0.0149    0.0800   -0.0022    0.1332   -0.0691   -0.6005   -0.0149    0.0800   -0.0022   -0.0001    0.0005   -0.0000    0.0011   -0.0008   -0.0036   -0.0001    0.0005   -0.0000    0.0006   -0.0031    0.0001   -0.0051    0.0026    0.0229    0.0006   -0.0031    0.0001   -0.0001    0.0006   -0.0000   -0.0013    0.0024   -0.0055   -0.0001    0.0006   -0.0000  Columns 19 through 24   -0.0310    0.0006    0.1653    0.0012   -0.0063    0.0002   -0.0414    0.0008    0.2408    0.0017   -0.0092    0.0004   -0.1160    0.0025    0.5958    0.0042   -0.0227    0.0006    0.0032   -0.0001   -0.0130   -0.0001    0.0005   -0.0000   -0.0156    0.0003    0.0800    0.0006   -0.0031    0.0001   -0.0021    0.0003   -0.0168   -0.0001    0.0006   -0.0000   -0.1073    0.0021    0.5748    0.0041   -0.0219    0.0006    0.0284   -0.0070    0.5619    0.0040   -0.0214    0.0007   -0.4076    0.0086    2.0945    0.0149   -0.0800    0.0022    0.0032   -0.0001   -0.0130   -0.0001    0.0005   -0.0000   -0.0156    0.0003    0.0800    0.0006   -0.0031    0.0001   -0.0021    0.0003   -0.0168   -0.0001    0.0006   -0.0000    0.0310   -0.0006   -0.1653   -0.0012    0.0063   -0.0002    0.0414   -0.0008   -0.2408   -0.0017    0.0092   -0.0004    0.1160   -0.0025   -0.5958   -0.0042    0.0227   -0.0006    0.0032   -0.0001   -0.0130   -0.0001    0.0005   -0.0000   -0.0156    0.0003    0.0800    0.0006   -0.0031    0.0001   -0.0021    0.0003   -0.0168   -0.0001    0.0006   -0.0000    0.1073   -0.0021   -0.5748   -0.0041    0.0219   -0.0006   -0.0284    0.0070   -0.5619   -0.0040    0.0214   -0.0007    0.4076   -0.0086   -2.0945   -0.0149    0.0800   -0.0022    0.0032   -0.0001   -0.0130   -0.0001    0.0005   -0.0000   -0.0156    0.0003    0.0800    0.0006   -0.0031    0.0001   -0.0021    0.0003   -0.0168   -0.0001    0.0006   -0.0000K>> Can anyone tell me what is wrong in the code? Why I am obtain kk as a singular matrix?regards,Hugo
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