as_cvxr_expr: Convert a value to a CVXR Expression

In CVXR: Disciplined Convex Optimization

Convert a value to a CVXR Expression

Description

Wraps numeric vectors, matrices, and Matrix package objects as CVXR Constant objects. Values that are already CVXR expressions are returned unchanged.

Usage

as_cvxr_expr(x)

Arguments

x	A numeric vector, matrix, Matrix::Matrix object, Matrix::sparseVector object, or CVXR expression.

Value

A CVXR expression (either the input unchanged or wrapped in Constant).

Matrix package interoperability

Objects from the Matrix package (dgCMatrix, dgeMatrix, ddiMatrix, sparseVector, etc.) are S4 classes. Because S4 dispatch preempts S7/S3 dispatch, raw Matrix objects cannot be used directly with CVXR operators (+, -, *, /, %*%, >=, ==, etc.).

Use as_cvxr_expr() to wrap a Matrix object as a CVXR Constant before combining it with CVXR variables or expressions. This preserves sparsity (unlike as.matrix(), which densifies).

Base R matrix and numeric objects work natively with CVXR operators — no wrapping is needed.

Examples

x <- Variable(3)

## Sparse Matrix needs as_cvxr_expr() for CVXR operator dispatch:
A <- Matrix::sparseMatrix(i = 1:3, j = 1:3, x = 1.0)
expr <- as_cvxr_expr(A) %*% x

## All operators work with wrapped Matrix objects:
y <- Variable(c(3, 3))
expr2 <- as_cvxr_expr(A) + y
constr <- as_cvxr_expr(A) >= y

## Base R matrix works natively (no wrapping needed):
D <- matrix(1:9, 3, 3)
expr3 <- D %*% x

CVXR documentation built on March 6, 2026, 9:10 a.m.