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Student Support Forum: 'Out of Memory in Simplify' topicStudent Support Forum > General > Archives > "Out of Memory in Simplify"

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Toshiyuki Meshii
04/23/97 9:19pm

Dear Sirs, Please help me on Simplify command. I was using Math v.2.2.4,
and the function I defined could be simplified in about 24 hours.
Note that my machine is a Pentium Pro 200MHz machine, with 128MB RAM
and with 1.0GB open hard disk space working under Win95. But the new
math v.3.0 has trouble in Simplifying the function. Though I am trying
MemoryConstrained[ Simplify[ McbyM[h1,h2,x], TimeConstraint -> 86400
], 50000000 ] the calculation is aborted with a message ''Out of Memory.
Exited.'' Please let me know a way to do simplification, at least
what ver. 2.0 could do. In addition, if it is possible, I do not want
to ch ange the constraints every time I execute Simplify. So I would
appreciate so much if you let me know the way to change the default
value. Here is the function. sa[t_] = Sinh[t]^2 - Sin[t]^2; aym[x_,z_]
= 1 / (2 beta^2 DY) / sa[x+z] * ( Sinh[x+z] ( Cosh[z] Sin[x] - Sinh[z]
Cos[x] ) - Sin[x+z] ( Cosh[x] Sin[z] - Sinh[x] Cos[z] ) ); aqm[x_,z_]
= 1 / (beta DY) / sa[x+z] * ( Sinh[x+z] Cosh[z] Cos[x] + Sin[x+z]
Cosh[x] Cos[z] ); ayp[x_,z_] = 1 / (2 beta^3 DY) / sa[x+z] * ( Sinh[x+z]
Cosh[z] Cos[x] - Sin[x+z] Cosh[x] Cos[z] ); aqp[x_,z_] = -1 / (2 beta^2
DY) / sa[x+z] * ( Sinh[x+z] ( Cosh[z] Sin[x] + Sinh[z] Cos[x] ) +
Sin[x+z] ( Cosh[x] Sin[z] + Sinh[x] Cos[z] ) ); ayps[x_,z_] = ayp[z,x];
ayms[x_,z_] = aym[z,x]; aqps[x_,z_] = -aqp[z,x]; aqms[x_,z_] = -aqm[z,x];
CC[h1_,h2_,x_] = { {ayps[h1,0]+ayp[0,h2], -ayms[h1,0]+aym[0,h2]},
{aqps[h1,0]+aqp[0,h2], -aqms[h1,0]+aqm[0,h2]+2 dm[x]} }; CCI[h1_,h2_,x_]
= Inverse[ CC[h1,h2,x] ]; BB[h1_,h2_] = { aym[h1,0] - ayms[0,h2],
aqm[h1,0] - aqms[0,h2] } ; { PcbyM[h1_,h2_,x_], McbyM[h1_,h2_,x_]
} = CCI[h1,h2,x].BB[h1,h2]; Simplify[McbyM[h1,h2,x]] The answer which
version 2.2.4 gave was as follows. (2 Cos[h1] Cosh[h1] - Cos[h1 +
2 h2] Cosh[h1] + 2 Cos[h2] Cosh[h2] - Cos[2 h1 + h2] Cosh[h2] - Cos[h2]
Cosh[2 h1 + h2] - Cos[h1] Cosh[h1 + 2 h2] + Sin[h1 + 2 h2] Sinh[h1]
+ Sin[2 h1 + h2] Sinh[h2] - Sin[h2] Sinh[2 h1 + h2] - Sin[h1] Sinh[h1
+ 2 h2]) / (2 - Cos[2 (h1 + h2)] - Cosh[2 (h1 + h2)] - 2 beta DY dm[x]
Sin[2 h1] + beta DY Cosh[2 h2] dm[x] Sin[2 h1] - 2 beta DY dm[x] Sin[2
h2] + beta DY Cosh[2 h1] dm[x] Sin[2 h2] + beta DY dm[x] Sin[2 (h1
+ h2)] + 2 beta DY dm[x] Sinh[2 h1] - beta DY Cos[2 h2] dm[x] Sinh[2
h1] + 2 beta DY dm[x] Sinh[2 h2] - beta DY Cos[2 h1] dm[x] Sinh[2
h2] - beta DY dm[x] Sinh[2 (h1 + h2)]) Thank you in advance.


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