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POising model from mathematica to matlab
 

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  1. POising model from mathematica to matlab
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    <p>i have this problem from mathematica,which refers to ising model.Here is a piece of code:</p> <pre><code>J1k = Table[2 RandomInteger[] - 1, {L}, {L}]; J2k = Table[2 RandomInteger[] - 1, {L}, {L}]; energy1 := Module[{ii1, ii2, jj1, jj2, kk1, kk2, dG1, ener1, ener2, ener}, ener = 0.; Do[ Do[ jj1 = ii1 + 1; jj2 = ii2 + 1; kk1 = ii1 - 1; kk2 = ii2 - 1; If[jj1 &gt; L, jj1 = 1]; If[jj2 &gt; L, jj2 = 1]; If[kk1 &lt; 1, kk1 = L]; If[kk2 &lt; 1, kk2 = L]; ener1 = -J1k[[ii1, ii2]]*mlat[[ii1, ii2]]*mlat[[jj1, ii2]] - J1k[[kk1, ii2]]*mlat[[ii1, ii2]]*mlat[[kk1, ii2]]; ener2 = -J2k[[ii1, ii2]]*mlat[[ii1, ii2]]*mlat[[ii1, jj2]] - J2k[[ii1, kk2]]*mlat[[ii1, ii2]]*mlat[[ii1, kk2]]; ener = ener1 + ener2 - 2*mlat[[ii1, ii2]] *\[Mu]Bk, {ii1, 1, L}], {ii2, 1, L}]; ener = ener/2.] energy = energy1 </code></pre> <p>Here is what i have done:</p> <pre><code>J1k=2*randint(L,L)-1; J2k=2*randint(L,L)-1; I have created a function: function Energy1 =energy1() %spin interaction with the neighbors ener=0; L=16; J1k=2*randint(L,L)-1; J2k=2*randint(L,L)-1; for ii2=1:L for ii1=1:L jj1=ii1+1;jj2=ii2+1;kk1=ii1-1;kk2=ii2-1; if (jj1&gt;L &amp; jj1==1) end if (jj2&gt;L &amp; jj2==1) end if (kk1&lt;1 &amp; kk1==L) end if (kk2&lt;1 &amp; kk2==L) end ener1=-J1k(ii1,ii2).*mlat(ii1,ii2).*mlat(jj1,ii2)-J1k(kk1,ii2).*mlat(ii1,ii2).*mlat(kk1,ii2); ener2=-J2k(ii1,ii2).*mlat(ii1,ii2).*mlat(ii1,jj2)-J2k(ii1,kk2).*mlat(ii1,ii2).*mlat(ii1,kk2); ener=ener1+ener2-2.*mlat(ii1,ii2).*mBk; end end ener=ener ./2; end </code></pre> <p>energy=@energy1</p> <p>The problem is that when i call energy "energy=@energy1" no value returns.It supposes to return a value "1" or "-1".</p> <p>Also, it continues (in mathematica ) :</p> <pre><code>T = 5.2; dT = 0.1; Umean = {}; energy = energy1; Do[energyseries = {}; T = T - dT; Do[i1 = RandomInteger[{1, L}]; i2 = RandomInteger[{1, L}]; j1 = i1 + 1; j2 = i2 + 1; k1 = i1 - 1; k2 = i2 - 1; If[j1 &gt; L, j1 = 1]; If[j2 &gt; L, j2 = 1]; If[k1 &lt; 1, k1 = L]; If[k2 &lt; 1, k2 = L]; dG1 = -J1k[[i1, i2]]*mlat[[j1, i2]] - J1k[[k1, i2]]*mlat[[k1, i2]]; dG2 = -J2k[[i1, i2]]*mlat[[i1, j2]] - J2k[[i1, k2]]*mlat[[i1, k2]]; dE = 2.*mlat[[i1, i2]] (dG1 + dG2 + \[Mu]Bk); W = N[Exp[-dE/T]]; If[W &lt; 1 &amp;&amp; W &gt; Random[] || dE &lt;= 0, mlat[[i1, i2]] = -mlat[[i1, i2]]; index = 1, index = 0]; energy = energy + dE*index // N; AppendTo[energyseries, energy], {i, 1, Maxstep}]; PrependTo[Umean, {T, Mean[energyseries]/L2}], {jT, 1, 51}]; </code></pre> <p>And i did :</p> <pre><code>T=5.2; dT=0.1; Umean=zeros(); energy=@energy1 for jT=1:51 energyseries=zeros(); T=T-dT; for i=1:Maxstep i1=randint(1,L); i2=randint(1,L); j1=i1+1; j2=i2+1; k1=i1-1; k2=i2-1; if (j1&gt;L &amp; j1==1) end if (j2&gt;L &amp; j2==1) end if (k1&lt;1 &amp; k1==L) end if (k2&lt;1 &amp; k2==L) end dG1=-J1k(i1,i2).*mlat(j1,i2)-J1k(k1,i2).*mlat(k1,i2); dG2=-J2k(i1,i2).*mlat(i1,j2)-J2k(i1,k2).*mlat(i1,k2); dE=2.*mlat(i1,i2).*(dG1+dG2+mBk); W=exp(-dE./T); if (W&lt;1 &amp; W&gt;rand() | dE&lt;=0) mlat(i1,i2)=-mlat(i1,i2); index=1; index=0; end energy=energy+dE.*index; energyseries(:)=[energy] end Umean(:)=[T mean(energyseries(:))./L2] end </code></pre> <p>which gives me message " Subscript indices must either be real positive integers or logicals.</p> <p>Error in ==> ising at 58 dG1=-J1k(i1,i2).*mlat(j1,i2)-J1k(k1,i2).*mlat(k1,i2);" Any ideas?</p>
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