mehdi jafari

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7 years, 37 days

MaplePrimes Activity


These are replies submitted by mehdi jafari

@jschulzb u are right.

@jschulzb u are right.

@Markiyan Hirnyk i think the answer is no since we define :
declare(y(x), prime=x):
here x is the primary variable ,y is the function of x,so its derivatives are also function of x,and i do not think x is the function of y'(x) since it is the priamary variable,evenif we can solve x with respect to y and y'(x),but it does not change the main issue,x IS the primary variable,and thus is independet of anything ,

@Markiyan Hirnyk i think the answer is no since we define :
declare(y(x), prime=x):
here x is the primary variable ,y is the function of x,so its derivatives are also function of x,and i do not think x is the function of y'(x) since it is the priamary variable,evenif we can solve x with respect to y and y'(x),but it does not change the main issue,x IS the primary variable,and thus is independet of anything ,

thanks alot,that's exactly what i needed.

thanks alot,that's exactly what i needed.

@Carl Love  yes,i face the same problem too,but when i use the code below,it does not use much memory,but a lot of time ,and i cancel the calculation.:

sol:=pdsolve(sys,[u,w,phi],HINT=`*`,singsol = false);

afterall,thnx alot for your attention and help,really thnx.

thanks for your help and support,but there is a little problem,and that is that when i use this procedure to solve my own problem,or at this problem,the matrix K1 is also fnction of b[i,j]s, but i want them to be solved just as functions of a[i]s,becuase i will assign nemerics to this a[i] and want to use them in a loop,so that i will need the inverse of the matrix K1,which in a 18*18 matrix take so many time if all of the elements are not numeric
what should i do? could u plz help?

thanks for your help and support,but there is a little problem,and that is that when i use this procedure to solve my own problem,or at this problem,the matrix K1 is also fnction of b[i,j]s, but i want them to be solved just as functions of a[i]s,becuase i will assign nemerics to this a[i] and want to use them in a loop,so that i will need the inverse of the matrix K1,which in a 18*18 matrix take so many time if all of the elements are not numeric
what should i do? could u plz help?thanks alot,and here is my own code : solve,K.mws

@Doug Meade no,i think  we can write them as MATRIX multiply to a VECTOR but i do not know how?, the matrix itself can be the function of the coefficients,thnx anyway.

@Markiyan Hirnykbut i thought u have took the file,and i had to do that,thnx anyway,

@Markiyan Hirnykbut i thought u have took the file,and i had to do that,thnx anyway,

@Markiyan Hirnyk i can not solve my equations since when using dsolve,it says that it has singularity,and when i want to solve them,using stiff=true options and maxfun=0,it takes more than a day to solve it.what can i do to solve them correctly?do u see any problem in the form of my equations?

when i see i can not solve it using dsolve,i want to solve it using step by step integration,and i need to convert these equations to vector mode,but now if u see there is a problem,all of components of the first equation are not included in the matrix u created,for example in the element first equations,all of multipleres of a[13] are not included,if u see in the pic,the coeeficient 0.1535e12*a[13]^2 is not in the line 13 of the matrix A(13,1)? i hope it will be clear enough,thnx.


@Markiyan Hirnyk i can not solve my equations since when using dsolve,it says that it has singularity,and when i want to solve them,using stiff=true options and maxfun=0,it takes more than a day to solve it.what can i do to solve them correctly?do u see any problem in the form of my equations?

when i see i can not solve it using dsolve,i want to solve it using step by step integration,and i need to convert these equations to vector mode,but now if u see there is a problem,all of components of the first equation are not included in the matrix u created,for example in the element first equations,all of multipleres of a[13] are not included,if u see in the pic,the coeeficient 0.1535e12*a[13]^2 is not in the line 13 of the matrix A(13,1)? i hope it will be clear enough,thnx.


@Markiyan Hirnyk could u plz email me so that i can send the file to your email?thank u for your attention ,

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