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- Thread starter Reem Hashem
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- #2

Avodyne

Science Advisor

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- #3

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m = NDSolve[{

y1'[t] == y5[t], y2'[t] == y6[t], y3'[t] == y7[t], y4'[t] == y8[t],

y5'[t] == y9[t], y6'[t] == y10[t], y7'[t] == y11[t], y8'[t] == y12[t],

y9'[t] == y13[t], y10'[t] == y14[t], y11'[t] == y15[t], y12'[t] == y16[t],

y13'[t] == -z^4 y1[t] + 2 z^2 y9[t] + z^2 w (-t + t^2) y17[t] + a y9[t],

y14'[t] == -z^4 y2[t] + 2 z^2 y10[t] + z^2 w (-t + t^2) y18[t] + a y10[t],

y15'[t] == -z^4 y3[t] + 2 z^2 y11[t] + z^2 w (-t + t^2) y19[t] + a y11[t],

y16'[t] == -z^4 y4[t] + 2 z^2 y12[t] + z^2 w (-t + t^2) y20[t] + a y12[t],

y17'[t] == y21[t], y18'[t] == y22[t], y19'[t] == y23[t], y20'[t] == y24[t],

y21'[t] == (-1 + 2 t) y1[t] + z^2 y17[t] - a y29[t],

y22'[t] == (-1 + 2 t) y2[t] + z^2 y18[t] - a y30[t],

y23'[t] == (-1 + 2 t) y3[t] + z^2 y19[t] - a y31[t],

y24'[t] == (-1 + 2 t) y4[t] + z^2 y20[t] - a y32[t],

y25'[t] == y29[t], y26'[t] == y30[t], y27'[t] == y31[t], y28'[t] == y32[t],

y29'[t] == -y21[t] + z^2 y25[t], y30'[t] == -y22[t] + z^2 y26[t],

y31'[t] == -y23[t] + z^2 y27[t], y32'[t] == -y24[t] + z^2 y28[t],

y1[0] == y2[0] == y3[0] == y4[0] == y5[0] == y6[0] == y7[0] == y8[0] ==

y10[0] == y11[0] == y12[0] == y13[0] == y15[0] == y16[0] == y17[0] ==

y18[0] == y19[0] == y20[0] == y21[0] == y22[0] == y24[0] == y25[0] ==

y26[0] == y27[0] == y28[0] == y29[0] == y30[0] == y31[0] == 0,

y9[0] == y14[0] == y23[0] == y32[0] == 1}, {y1, y2, y3, y4, y5,

y6, y7, y8, y9, y10, y11, y12, y13, y14, y15, y16, y17, y18,

y19, y20, y21, y22, y23, y24, y25, y26, y27, y28, y29, y30, y31,

y32}, {t, 0, 1}];

f[1, 1] = y1[1] /. m;

f[1, 2] = y2[1] /. m;

f[1, 3] = y3[1] /. m;

f[1, 4] = y4[1] /. m;

f[2, 1] = y5[1] /. m;

f[2, 2] = y6[1] /. m;

f[2, 3] = y7[1] /. m;

f[2, 4] = y8[1] /. m;

f[3, 1] = y17[1] /. m;

f[3, 2] = y18[1] /. m;

f[3, 3] = y19[1] /. m;

f[3, 4] = y20[1] /. m;

f[4, 1] = y25[1] /. m;

f[4, 2] = y26[1] /. m;

f[4, 3] = y27[1] /. m;

f[4, 4] = y28[1] /. m;

d = Array[f, {4, 4}];

d = Partition[Flatten[d], 4];

b = Det[d]];

tmp[0, 3.7, 1000]

Out[2]= 15.7127

- #4

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and thanks in advance.

- #5

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This might help.

http://reference.wolfram.com/mathematica/tutorial/DefiningFunctions.html

This

Plot[tmp[0, 3.7, w], {w, 1000, 100000}]

shows how your function behaves.

But this

FindRoot[tmp[0, 3.7, w] == 0, {w, 95000, 90000, 100000}]

fails for some reason I haven't been able to isolate in your code.

This

Plot[tmp[0, 3.7, w], {w, 90000, 95000}]

can give you a good estimate.

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