How can i solve these two equations simultaneously for A and B ?

조회 수: 1 (최근 30일)
Asif Arshid
Asif Arshid 2016년 8월 26일
편집: Asif Arshid 2016년 8월 27일
I have a system of 16 equations with 4 integration constants (A, B, C and D) in each soil layer (4 layers) and each soil layer has 4 stress-strain equations. I need to solve them simultaneously for 16 constants.
Below is the simplified form of two equations, which i am trying to solve for A and B.
int(5*besselj(0,x)*besselj(1, 0.5*x)*x*(A+5) ,x,0,10) = 0;
int(5*besselj(0,x)*besselj(1, 0.8*x)*x*(A+B) ,x,0,10) = A;

채택된 답변

Walter Roberson
Walter Roberson 2016년 8월 27일
The multiply by (A+5) in the first equation leads to the trivial solution A=-5, zeroing the effect of the besselj .
You can substitute A into the second equation and then do a numeric solve, restriction your range for B from 5 onwards; the numeric solution turns out to be about B = 5.57463755753316
  댓글 수: 1
Asif Arshid
Asif Arshid 2016년 8월 27일
편집: Asif Arshid 2016년 8월 27일
Thank you Walter Roberson for your quick reply. During my hit and trials of different functions, I got "vpasolve", it helped to solve for the equations upto the precision i was looking for.
z1 = int(5*besselj(0,x)*besselj(1,0.8*x)*x*(A+5),x,0,10);
z2 = int(5*besselj(0,x)*besselj(1,0.7*x)*x*(A+B),x,0,10);
[A, B] = vpasolve([z1==0, z2==A], [A, B])
One can equate z1 and z2 to any constant, variable or even functions of A and B, it will give you the approximate solution with reasonable precision. Thanks a lot again.

댓글을 달려면 로그인하십시오.

추가 답변 (0개)

카테고리

Help CenterFile Exchange에서 Symbolic Math Toolbox에 대해 자세히 알아보기

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by