# Modelling Frobenius norm of Matrix using one SecondOrderCone() constraint
**URL:** https://discourse.julialang.org/t/modelling-frobenius-norm-of-matrix-using-one-secondordercone-constraint/23881
**Category:** Optimization (Mathematical)
**Tags:** question
**Created:** [May 5, 2019, 6:04pm UTC](https://discourse.julialang.org/t/modelling-frobenius-norm-of-matrix-using-one-secondordercone-constraint/23881 "2019-05-05T18:04:33Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@ryancorywright](https://discourse.julialang.org/u/ryancorywright)
#### Post date: [May 5, 2019, 6:04pm UTC](https://discourse.julialang.org/t/modelling-frobenius-norm-of-matrix-using-one-secondordercone-constraint/23881/1 "2019-05-05T18:04:33Z")
Hi all,
I was wondering if it is possible to model the Frobenius norm of a matrix using a single second order cone constraint in JuMP 0.19 (perhaps by reshaping the matrix).
In JuMP 0.18.5 this was possible via:
@variable(m, X[1:n, 1:m])
@constraint(m, t\>=norm(X))
In JuMP 0.19 I can certainly model a Frobenius norm with min(n,m) second order cone constraints, via
@variable(m, t[i=1:n]\>=0.0)
@constraint(m, defineSOC[i=1:n], [t[i]; X[i,:]] in SecondOrderCone())
but for performance reasons it would be better to use one SecondOrderCone.
Thanks!
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### Author:  [@blegat](https://discourse.julialang.org/u/blegat)
#### Post date: [May 5, 2019, 7:09pm UTC](https://discourse.julialang.org/t/modelling-frobenius-norm-of-matrix-using-one-secondordercone-constraint/23881/2 "2019-05-05T19:09:32Z")
Why don’t you do `@constraint(model, [t; vec(X)] in SecondOrderCone())` ?
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### Author:  [@ryancorywright](https://discourse.julialang.org/u/ryancorywright)
#### Post date: [May 5, 2019, 9:21pm UTC](https://discourse.julialang.org/t/modelling-frobenius-norm-of-matrix-using-one-secondordercone-constraint/23881/3 "2019-05-05T21:21:40Z")
Exactly what I was looking for, thanks!