# 'MultiVector' not updating in a loop
**URL:** https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410
**Category:** General Usage
**Created:** [July 18, 2022, 3:12pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410 "2022-07-18T15:12:52Z")
**Posts on this page:** 15
**Page:** 1
### Author:  [@fsmith001](https://discourse.julialang.org/u/fsmith001)
#### Post date: [July 18, 2022, 3:12pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/1 "2022-07-18T15:12:53Z")
Hello, I am using a for loop to insert values into a DenseMultiVector, a type that was created in the project I am continuing work on. I start by initializing an undef DenseMultiVector of the correct size, and then loop through by assigning each index of the DenseMultiVector with a new value. The new value, a sum, is being calculated correctly, but only the first value in each vector is being updated correctly. Any ideas of what the issue is?
Here is the code:
```
comm = SerialComm{Int, Int, Int}()
map = BlockMap(numVects, length, comm)
data = Array{Float32}(undef, length, numVects)
result = DenseMultiVector{}(map, data)
A = scale!(A, a)
B = scale!(B, b)
for i = 1:numVectors(A)
for j = 1:localLength(A)
sum = A[i,j] + B[i,j]
result[i,j] = sum
end
end
```
---
### Author:  [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)
#### Post date: [July 18, 2022, 8:37pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/2 "2022-07-18T20:37:46Z")
A couple of comments:
1. `scale!` hasn’t been around for a long, long time (Julia 0.6 maybe?). Please update to a recent version of Julia.
2. You are using several variables whose names are the same as built-in Julia functions, such as `sum`, `map`.
3. Please provide a runnable minimal working example (MWE), item 4 in [this](https://discourse.julialang.org/t/psa-make-it-easier-to-help-you/14757/93) post.
---
### Author:  [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)
#### Post date: [July 18, 2022, 9:02pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/3 "2022-07-18T21:02:05Z")
> [@fsmith001](#):
>
> continuing
It sounds like you might be trying to resurrect an old pre-1.0 project. To help you bring your code up to date with current Julia, you can install Julia 0.7 from [here](https://julialang.org/downloads/oldreleases/) and run your code under that version. It will provide messages telling you what’s obsolete and what to replace the obsolete parts with.
---
### Author:  [@fsmith001](https://discourse.julialang.org/u/fsmith001)
#### Post date: [July 19, 2022, 5:00pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/4 "2022-07-19T17:00:51Z")
The scale! function I am using here is not a built-in Julia function, it was written by the previous author of the project I am working on, specifically for type MultiVector.
```
using JuliaPetra
function update(a, A::MultiVector, b, B::MultiVector)
if numVectors(A) == numVectors(B) && localLength(A) == localLength(B)
myComm = SerialComm{Int, Int, Int}()
myMap = BlockMap(numVectors(A), localLength(A), myComm)
data = Array{Float32}(undef, localLength(A), numVectors(A))
result = DenseMultiVector{}(myMap, data)
A = scale!(A, a)
B = scale!(B, b)
for i = 1:numVectors(A)
for j = 1:localLength(A)
result[i,j] = A[i,j] + B[i,j]
end
end
else
println("Error: MultiVectors must be the same size")
end
return result
end
```
Is this more helpful?
\*I would also like to note that when I printed out what A[i,j] + B[i,j] is in each iteration, the sum is correct which tells me the problem is in putting some of those values into the result MultiVector.
---
### Author:  [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)
#### Post date: [July 19, 2022, 6:03pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/5 "2022-07-19T18:03:43Z")
It would help a lot to see what the definition of `DenseMultiVector` is. Better yet would be a runnable MWE, to avoid misconceptions based on insufficient knowledge of your code (like my `scale!` comment).
Did you also try printing out the value of `result[i,j]` in the loop, say with a
```julia
@show result[i,j]
```
in the line right after the assignment?
---
### Author:  [@fsmith001](https://discourse.julialang.org/u/fsmith001)
#### Post date: [July 19, 2022, 6:49pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/6 "2022-07-19T18:49:02Z")
Thank you for your help with this!
This is part of the project JuliaPetra (as I mentioned “using JuliaPetra”) so I’m not sure the best way to show you all the code, but here is the DenseMultiVector constructors:
```
function DenseMultiVector{Data}(map::BlockMap{GID, PID, LID}, numVecs::Integer, zeroOut=true) where {Data <: Number, GID <: Integer, PID <: Integer, LID <: Integer}
localLength = numMyElements(map)
if zeroOut
data = zeros(Data, (localLength, numVecs))
else
data = Array{Data, 2}(undef, localLength, numVecs)
end
DenseMultiVector{Data, GID, PID, LID}(data, numVecs, map)
end
function DenseMultiVector(map::BlockMap{GID, PID, LID}, data::AbstractArray{Data, 2}) where {Data <: Number, GID <: Integer, PID <: Integer, LID <: Integer}
localLength = numMyElements(map)
if size(data, 1) != localLength
throw(InvalidArgumentError("Length of vectors does not match local length indicated by map"))
end
DenseMultiVector{Data, GID, PID, LID}(data, size(data, 2), map)
end
```
and then how I construct it to run the update function:
```
function update(a, A::MultiVector, b, B::MultiVector)
if numVectors(A) == numVectors(B) && localLength(A) == localLength(B)
myComm = SerialComm{Int, Int, Int}()
myMap = BlockMap(numVectors(A), localLength(A), myComm)
data = Array{Float32}(undef, localLength(A), numVectors(A))
result = DenseMultiVector{}(myMap, data)
A = scale!(A, a)
B = scale!(B, b)
for i = 1:numVectors(A)
for j = 1:localLength(A)
result[i,j] = A[i,j] + B[i,j]
end
end
else
println("Error: MultiVectors must be the same size")
end
return result
end
v1 = DenseMultiVector(curMap, ones(Float64, 2, 2))
v2 = DenseMultiVector(curMap, ones(Float64, 2, 2))
println("Update: ", update(2, v1, 3, v2))
```
What I expect is for the result to print [5.0 5.0; 5.0 5.0] but what is printed is [5.0 0.0; 5.0 0.0]. And when I do @show result[i,j] after it’s assignment, it prints: 5.0 0.0 5.0 0.0, just as is shown in the result.
---
### Author:  [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)
#### Post date: [July 19, 2022, 7:41pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/7 "2022-07-19T19:41:40Z")
Both of the methods you supplied for `DenseMultiVector` end with a call to what looks like a constructor method to the `DenseMultiVector` type, which would be defined in your package with a `struct` or `mutable struct` statement. Could you also please post that code? Also, since you are able to index into a `DenseMultiVector` there must be code that implements the `getindex` and `setindex!` methods for this type. Please post these as well.
---
### Author:  [@fsmith001](https://discourse.julialang.org/u/fsmith001)
#### Post date: [July 20, 2022, 3:02pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/8 "2022-07-20T15:02:26Z")
Here’s what I have for what you mentioned - thank you.
```
mutable struct DenseMultiVector{Data <: Number, GID <: Integer, PID <: Integer, LID <: Integer} <: MultiVector{Data, GID, PID, LID}
data::Array{Data, 2}
numVectors::LID
map::BlockMap{GID, PID, LID}
end
function Base.getindex(A::MultiVector, row::Integer, col::Integer)
@boundscheck begin
if !(1<=col<=numVectors(A))
throw(BoundsError(A, (row, col)))
end
end
lRow = lid(getMap(A), row)
@boundscheck begin
if lRow < 1
throw(BoundsError(A, (row, col)))
end
end
@inbounds value = getLocalArray(A)[lRow, col]
value
end
function Base.getindex(A::MultiVector, i::Integer)
if numVectors(A) != 1
throw(ArgumentError("Can only use single index if there is just 1 vector"))
end
lRow = lid(getMap(A), i)
@boundscheck begin
if lRow < 1
throw(BoundsError(A, I))
end
end
@inbounds value = getLocalArray(A)[lRow, 1]
value
end
function Base.setindex!(A::MultiVector, v, row::Integer, col::Integer)
@boundscheck begin
if !(1<=col<=numVectors(A))
throw(BoundsError(A, (row, col)))
end
end
lRow = lid(getMap(A), row)
@boundscheck begin
if lRow < 1
throw(BoundsError(A, (row, col)))
end
end
@inbounds getLocalArray(A)[lRow, 1] = v
v
end
function Base.setindex!(A::MultiVector, v, i::Integer)
if numVectors(A) != 0
throw(ArgumentError("Can only use single index if there is just 1 vector"))
end
lRow = lid(getMap(A), i)
@boundscheck begin
if lRow < 1
throw(BoundsError(A, I))
end
end
@inbounds getLocalArray(A)[lRow, 1] = v
v
end
```
---
### Author:  [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)
#### Post date: [July 20, 2022, 4:37pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/9 "2022-07-20T16:37:17Z")
Thanks. I can guess at the purpose of some of the functions referenced above, but that would be dangerous, especially when we’re on a bug hunt. So please also provide the codes that define `numVectors`, `lid`, `getMap`, `getLocalArray`, `BlockMap`, and `localLength`.
Note: This tedious back and forth is why it would be much easier to work with a complete MWE.
Note 2: I won’t be able to look at this further for a few hours.
---
### Author:  [@DNF](https://discourse.julialang.org/u/DNF)
#### Post date: [July 20, 2022, 7:06pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/10 "2022-07-20T19:06:54Z")
With respect to the `getindex`/`setindex!`, methods, what is the purpose of doing manual bounds checks, and the call
> [@fsmith001](#):
>
> `@inbounds value = getLocalArray(A)[lRow, col]`
?
Why not just rely on the automatic bounds checks? Doing manual checks seems like a risk of creating exactly the sort of weird bugs you are seeing.
---
### Author:  [@fsmith001](https://discourse.julialang.org/u/fsmith001)
#### Post date: [July 25, 2022, 4:23pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/11 "2022-07-25T16:23:39Z")
```
function numVectors end
function getLocalArray end
numVectors(mVect::DenseMultiVector) = mVect.numVectors
getMap(mVect::DenseMultiVector) = mVect.map
getLocalArray(mVect::DenseMultiVector) = mVect.data
@inline function lid(map::BlockMap{GID, PID, LID}, gid::Integer) where GID <: Integer where PID <: Integer where LID <: Integer
data = map.data
if (gid < data.minMyGID) || (gid > data.maxMyGID)
LID(0)
elseif data.linearMap
LID(gid - data.minMyGID + 1)
elseif gid >= data.myGlobalElements[1] && gid <= data.lastContiguousGID
LID(gid - data.myGlobalElements[1] + 1)
elseif haskey(data.lidHash, GID(gid))
data.lidHash[gid]
else
LID(0)
end
end
struct BlockMap{GID <: Integer, PID <:Integer, LID <: Integer}
data::BlockMapData{GID, PID, LID}
function BlockMap{GID, PID, LID}(data::BlockMapData) where {GID <: Integer, PID <:Integer, LID <: Integer}
new(data)
end
end
```
\*\*I also got rid of the bounds checks in getIndex! and setIndex! but the problem persists.
(Also, what would be the best way for me to share all the code needed to solve this issue?)
---
### Author:  [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)
#### Post date: [July 25, 2022, 7:49pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/12 "2022-07-25T19:49:43Z")
Thanks, I’ll look at this as soon as I’m able. If others want to jump in, they’re welcome as far as I’m concerned.
An easy way to share a large amount of code is a [gist](https://docs.github.com/en/get-started/writing-on-github/editing-and-sharing-content-with-gists/creating-gists), or if you need to retain the directory structure of many files, just a standard Github repository.
---
### Author:  [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)
#### Post date: [July 25, 2022, 8:36pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/13 "2022-07-25T20:36:10Z")
I’m afraid that the `BlockMap` definition makes use of a so far undefined type `BlockMapData` which is also needed.
@fsmith001 : We could save some time by having you perform the same steps that I’ve been doing. As you provide each new block of code, I’ve been accumulating them in a single file, with the `update` function and its invocation positioned at the end of the file. I then try `include`-ing this file into a running Julia session, which quickly shows me what is still required for the code to compile and execute. If you could do this on your end and then post the file somewhere (such as in a gist or repository as I mentioned in my previous post), we could likely find your problem pretty quickly.
---
### Author:  [@fsmith001](https://discourse.julialang.org/u/fsmith001)
#### Post date: [July 26, 2022, 4:42pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/14 "2022-07-26T16:42:40Z")
Okay, thank you! I did as you suggested, here is the link to the gist: [trying to make the update() function work properly · GitHub](https://gist.github.com/fsmith001/28ef87b38c3b3a8e5b72cf6e0b5e0fb8)
I think I see now where the problem is, but am not sure how to fix it. It seems that BlockMapData is not properly used based on how it is defined, however I do not know what exactly the issue is and how to use it correctly. Does this make sense?
---
### Author:  [@PeterSimon](https://discourse.julialang.org/u/PeterSimon)
#### Post date: [July 26, 2022, 8:19pm UTC](https://discourse.julialang.org/t/multivector-not-updating-in-a-loop/84410/15 "2022-07-26T20:19:39Z")
Let’s continue the discussion on the gist.