线性方程组的求解系统R-验证

Question

So I managed to solve this system of linear equations in R:

x–y+z=1, x+y–z=1 and x+y+z=3

My code below is:

A <- matrix(data=c(1, -1, 1, 1, 1, -1, 1, 1, 1), nrow=3, ncol=3, byrow=TRUE) 

b <- matrix(data=c(1, 1, 3), nrow=3, ncol=1, byrow=FALSE)

round(solve(A, b), 3)

However, I need to demonstrate my solution is correct by substituting values for x, y and z. Apparently this is easily done with one line of code using matrix operations. Can anyone help me out? Thanks in advance.

Answer 1

You gave the equations with a minus sign that was actually a dash, but after correcting that error we can transmute those equations and assess the solution. In this case the result is exact, but in most other instances you would probably want to cast the tests using all.equal .

eval( substitute( x-y+z==1 && x+y-z==1 && x+y+z==3, list(x=1,y=1,z=1) ) )
[1] TRUE

Before the recognition that "-" is not the same as "–" I was getting:

Error: unexpected input in "eval( substitute( x‚"