I have a set of linear equations and would like to find any feasible solution.
A simplex solution works in Case 1 below, but not in Case 2. I would be
grateful for any help.
Case 1: Find any feasible solution for the set of linear equations:
a + b + c = 5
a + b + 0c = 4
0a + b + c = 4
Solution - a feasible (and unique) solution is a=1, b=3, c=1.
The following R code returns a feasible solution:
A3M = matrix(c(1,1,0,1,1,1,1,0,1),nrow=3)
b3M = matrix(c(5,4,4),ncol=1)
A1M = matrix(c(1,0,0,0,1,0,0,0,1),nrow=3)
b1M = matrix(c(10,10,10),ncol=1)
AM = matrix(c(1,1,1),nrow=1)
simplex(a = AM, A1 = A1M, b1 = b1M, A2 = NULL, b2 = NULL, A3 = A3M, b3 = b3M,
maxi = TRUE)
Case 2: Find any feasible solution for the set of linear equations
a + b + c = 5
a + 0b + c = 2
0a + b + 0c = 3
Solution - one feasible solution of many is a=1, b=3, c=1. There are infinite
possible solutions in Case 2.
However, the following R code fails to return any feasible solution:
A3M = matrix(c(1,1,0,1,0,1,1,1,0),nrow=3)
b3M = matrix(c(5,2,3),ncol=1)
A1M = matrix(c(1,0,0,0,1,0,0,0,1),nrow=3)
b1M = matrix(c(10,10,10),ncol=1)
AM = matrix(c(1,1,1),nrow=1)
simplex(a = AM, A1 = A1M, b1 = b1M, A2 = NULL, b2 = NULL, A3 = A3M, b3 = b3M,
maxi = TRUE)
The code returns the error:
Error in A.out[, basic] <- iden(M) : subscript out of bounds
Am I using the Simplex function incorrectly? There may be a better way to
approach the problem of finding a feasible solution.
Cheers,
Chris.
The contents of this email including any attachments are confidential. If you
have received this email in error, please advise the sender by return email and
delete this email. Any unauthorised use of the contents of the email is
prohibited and you must not disseminate, copy or distribute the message or use
the information contained in the email or its attachments in any way.
The views or opinions expressed are the author's own and may not reflect the
views or opinions of Tibra. Tibra does not guarantee the integrity of any
emails or attached files. E-mails may be interfered with, may contain computer
viruses or other defects. Under no circumstances do we accept liability for any
loss or damage which may result from your receipt of this message or any
attachments.
[[alternative HTML version deleted]]
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
