CODEWITHSUNDEEP
julia
Satyaban Sahoo
Satyaban Sahoo

Reputation: 117

MethodError: no method matching isless(::Matrix{Float64}, ::Matrix{Float64})

Code - Quasi Newton Problem

This is the code for Quasi Newton Problem. For this, I am getting an error

MethodError: no method matching isless(::Matrix{Float64}, ::Matrix{Float64})
Closest candidates are:
  isless(::Any, ::Missing) at missing.jl:88
  isless(::Missing, ::Any) at missing.jl:87

Stacktrace:
  [1] <(x::Matrix{Float64}, y::Matrix{Float64})
    @ Base .\operators.jl:279
  [2] >(x::Matrix{Float64}, y::Matrix{Float64})
    @ Base .\operators.jl:305
  [3] bracket_minimum(f::var"#45#46"{typeof(k), Matrix{Float64}, Matrix{Float64}}, x::Int64; s::Float64, k::Float64)
    @ Main .\In[122]:12
  [4] bracket_minimum(f::Function, x::Int64) (repeats 2 times)
    @ Main .\In[122]:10
  [5] line_search(f::typeof(k), x::Matrix{Float64}, d::Matrix{Float64})
    @ Main .\In[122]:35
  [6] step!(M::BFGS, f::Function, ∇f::typeof(l), x::Matrix{Float64})
    @ Main .\In[122]:48
  [7] quasi_method(f::typeof(k), g::Function, x0::Matrix{Float64})
    @ Main .\In[122]:67
  [8] top-level scope
    @ In[128]:3
  [9] eval
    @ .\boot.jl:360 [inlined]
 [10] include_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)
    @ Base .\loading.jl:1116

I still couldn't figure what's the issue with line 10 and 12. So help me out here? Maybe it's due to Matrix we are using or some other issues, I couldn't debug.

Upvotes: 1

Views: 1603

Answers (1)

Przemyslaw Szufel
Przemyslaw Szufel

Reputation: 42194

You forgot to vectorize your code. See the example below for reference:

julia> a=[1. 2.; 3. 4.]; b=[1. 3.; 5. 7.];

julia> a < b
ERROR: MethodError: no method matching isless(::Matrix{Float64}, ::Matrix{Float64})

Now let us add dot to vectorize:

julia> a .< b
2×2 BitMatrix:
 0  1
 1  1

If you want to check if all elements are lower use all:

julia> all(a .< b)
false

In your code bracket_minimum does the comparison yc > yb and those values are matrices while your code expects scalars.

Upvotes: 2

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