[R] Problem with function gp in package cccp

[Jeff Reichman]

In gp(F0, g0, A = A, b = b) : No restrictions provided, trying solve()


This likely means that while you've specified A and b, the solver doesn't
recognize any inequality (<=) or equality (=) restrictions - because in the
context of the gp() function from the CVXR or similar geometric programming
libraries in R, you're expected to provide explicit inequality/equality
markers or properly formatted constraint matrices.

So what's missing? Probably an argument like ineq = ... or eq = ... to
declare the type of constraint.

Here's how to express your constraint properly, assuming the library expects
inequalities or equalities to be marked explicitly:

# Properly declare equality constraints
gp(F0, g0, eq=A, eq.b=b)

Or possibly (depending on the package):

gp(F0, g0, Aeq=A, beq=b)

If the solver expects inequality constraints:

gp(F0, g0, A=A, b=b, meq=1)  # Indicating 1 equality constraint

Jeff Reichman


-----Original Message-----
From: R-help <r-help-bounces using r-project.org> On Behalf Of
koller using science.iwi.ac.at
Sent: Wednesday, July 30, 2025 2:32 PM
To: r-help using r-project.org
Subject: [R] Problem with function gp in package cccp

Dear all!

I tried to solve a simple test example of a geometric program:
minimize x + y   s.t.   xy = 1
The solution should be (1, 1).

I tried:
F0 <- diag(2)                  #  [m * n] m = number of terms of the 
posynomial, n = number of variables
g0 <- log(matrix(1,2,1))       #  [m * 1]
A <-  matrix(c(1,1), 1, 2)     #  one constraint, one row
b <-  log(matrix(1,1,1))
RES <- gp(F0, g0, A=A, b=b)

Though I received the correct solution, the function gives a warning:
In gp(F0, g0, A = A, b = b) : No restrictions provided, trying solve().

Also, when I try
RES <- gp(F0, g0, A="A", b=b)
or
gp(F0, g0)

receiving the same result, I find out, that my equality constraints are not
considered at all.

In my view, the unconstraint problem should have (0, 0) as a solution, btw.

Am I missing something fundamental?

Thanks in advance!

Wolfgang
	[[alternative HTML version deleted]]

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