# max(A, A') gives isless() error
**URL:** https://discourse.julialang.org/t/max-a-a-gives-isless-error/87165
**Category:** General Usage
**Created:** [September 12, 2022, 9:52pm UTC](https://discourse.julialang.org/t/max-a-a-gives-isless-error/87165 "2022-09-12T21:52:51Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@m\_shah2](https://discourse.julialang.org/u/m_shah2)
#### Post date: [September 12, 2022, 9:52pm UTC](https://discourse.julialang.org/t/max-a-a-gives-isless-error/87165/1 "2022-09-12T21:52:51Z")
I am trying to generate a graph G by taking maxof SparseArrays.SparseMatrixCSC{Float64, Int64}
and LinearAlgebra.Adjoint{Float64, SparseArrays.SparseMatrixCSC{Float64, Int64}}
But it throws me an error when I do
G = max(A, A’); # undirected version of graph
My original code is:
Pkg.add(“MAT”)
Pkg.build(“MAT”)
Pkg.add(“PyPlot”)
Pkg.build(“PyPlot”)
Pkg.add(“MatrixNetworks”)
Pkg.build(“MatrixNetworks”)
Pkg.add(“PyCall”)
Pkg.build(“PyCall”)
using MatrixNetworks
using MAT
using PyPlot
using PyCall
data = matread(“data/neuronal.mat”);
A = data[“A”];
G = max(A, A’);
It runs fine till A, but throws error at G. Don’t know how to solve it.
I tried import Base: isless but no help.
This is the error:
MethodError: no method matching isless(::LinearAlgebra.Adjoint{Float64, SparseArrays.SparseMatrixCSC{Float64, Int64}}, ::SparseArrays.SparseMatrixCSC{Float64, Int64})
Closest candidates are:
isless(::Any, ::Missing) at missing.jl:88
isless(::Missing, ::Any) at missing.jl:87
isless(::Any, ::PyObject) at C:\Users\Manish.julia\packages\PyCall\ygXW2\src\pyoperators.jl:76
…
Stacktrace:
[1] max(x::SparseArrays.SparseMatrixCSC{Float64, Int64}, y::LinearAlgebra.Adjoint{Float64, SparseArrays.SparseMatrixCSC{Float64, Int64}})
@ Base .\operators.jl:480
[2] top-level scope
@ In[29]:1
[3] eval
@ .\boot.jl:368 [inlined]
[4] include\_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)
@ Base .\loading.jl:1428
---
### Author:  [@DNF](https://discourse.julialang.org/u/DNF)
#### Post date: [September 12, 2022, 10:02pm UTC](https://discourse.julialang.org/t/max-a-a-gives-isless-error/87165/2 "2022-09-12T22:02:16Z")
In order to calculate `max(A, A')` it must be possible to say which one is ‘greater’, and `isless` helps with that comparison.
But what is greater of `A` and `A'`? I don’t think there is any obvious answer to that question.
My guess is that you probably want to compare element-by-element, and to do that you can use broadcasting:
```julia
max.(A, A')
```
Notice the dot after `max`. This should return a matrix with pairwise comparisons of all elements.
Take a look at the broadcasting section of the manual for more information: [Multi-dimensional Arrays · The Julia Language](https://docs.julialang.org/en/v1/manual/arrays/#Broadcasting)
---
### Author:  [@m\_shah2](https://discourse.julialang.org/u/m_shah2)
#### Post date: [September 12, 2022, 10:24pm UTC](https://discourse.julialang.org/t/max-a-a-gives-isless-error/87165/3 "2022-09-12T22:24:44Z")
This helped. Thanks a lot.