# Bigfloat lufact

**URL:** <https://discourse.julialang.org/t/bigfloat-lufact/4653>\
**Category:** Numerics\
**Tags:** linearalgebra\
**Created:** [July 4, 2017, 11:34pm UTC](https://discourse.julialang.org/t/bigfloat-lufact/4653 "2017-07-04T23:34:09Z")\
**Posts on this page:** 1\
**Showing post:** 3

<div class="post-metadata">

**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [July 5, 2017, 1:10am UTC](https://discourse.julialang.org/t/bigfloat-lufact/4653/3 "2017-07-05T01:10:55Z")

</div>

I pulled an example out. In this case, it looks like `lufact!` is the only one correct on BigFloat:

```julia
A = 92.317*eye(4)
b = [0.0970454, 0.00944241, 0.167562, 0.08518]
println("True solution")
println(b/92.317)

lufact!(A)
println("lufact")
println(A\b)

A = 92.317*eye(4)

qrfact!(A)
println("qrfact")
println(A\b)

A = 92.317*eye(4)

svdfact!(A)
println("svdfact")
println(A\b)

Abig = big.(A)
bbig = big.(b)

lufact!(Abig)
println("lufact bigfloat")
println(Float64.(Abig\bbig))

Abig = big.(A)

qrfact!(Abig)
println("qrfact bigfloat")
println(Float64.(Abig\bbig))

Abig = big.(A)

using GenericSVD
svdfact!(Abig)
println("generic svdfact bigfloat")
println(Float64.(Abig\bbig))

```

This prints out the following:

```julia
True solution
[0.00105122, 0.000102282, 0.00181507, 0.00092269]
lufact
[0.00105122, 0.000102282, 0.00181507, 0.00092269]
qrfact
[0.00105122, 0.000102282, 0.00181507, 0.00092269]
svdfact
[0.00105122, 0.000102282, 0.00181507, 0.00092269]
lufact bigfloat
[0.00105122, 0.000102282, 0.00181507, 0.00092269]
qrfact bigfloat
[-0.00105122, -0.000102282, -0.00181507, 0.00092269]
generic svdfact bigfloat
[0.0485227, 0.00472121, 0.083781, 0.04259]

```

Now I’m getting really confused. There’s definitely something odd in GenericSVD though.

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