MATLAB Answers

0

Solve systems of linear equations Ax = B for x

x = A\B solves the system of linear equations A*x = B. The matrices A and B must have the same number of rows.
But ,what is the operation between the rows?
There is any one can solve this example–manually ?
A =
1 3
4 2
b= [6 ;7];
>> A\b
ans =
0.9000
1.7000
How to find 0.9 and 1.7 exactly?

  댓글 수: 0

로그인 to comment.

답변 수: 3

Stephen Cobeldick 님의 답변 29 Aug 2019
Stephen Cobeldick 님이 편집함. 29 Aug 2019
 채택된 답변

"But ,what is the operation between the rows?"
Both mldivide and mrdivide can use many different algorithms for solving systems of linear equations, as documented in the mldivide documentation. There is no single "operation" that describes all of those algorithms.
"There is any one can solve this example–manually ?"
This is easy using standard definitions for solving linear equations, e.g. elimination of variables:
System definition:
First solve the first equation for x:
Second, substitute x back into the second equation:
Third, solve that for y:
And finally try them with your example values:
>> A = [1,3;4,2]
A =
1 3
4 2
>> b = [6;7]
b =
6
7
>> A\b
ans =
0.9
1.7
>> y = (A(1,1)*b(2)-A(2,1)*b(1)) ./ (A(1,1)*A(2,2)-A(2,1)*A(1,2))
y =
1.7
>> x = (b(1)-A(1,2)*y) ./ A(1,1)
x =
0.9

  댓글 수: 0

로그인 to comment.


KALYAN ACHARJYA 님의 답변 29 Aug 2019
KALYAN ACHARJYA 님이 편집함. 29 Aug 2019

ans =
0.9000
1.7000
How to find 0.9 and 1.7 exactly??
format shortg;
A =[1 3
4 2];
b= [6 ;7];
A\b
Result:
ans =
0.9
1.7

  댓글 수: 0

로그인 to comment.


Torsten 님의 답변 29 Aug 2019

https://en.wikipedia.org/wiki/Cramer%27s_rule

  댓글 수: 0

로그인 to comment.



Translated by