# Ccall: could not find function \*\* in library /usr/local/cuda-7.0/lib64/libcusolver.so.7.0.28

**URL:** <https://discourse.julialang.org/t/ccall-could-not-find-function-in-library-usr-local-cuda-7-0-lib64-libcusolver-so-7-0-28/10009>\
**Category:** GPU\
**Created:** [March 27, 2018, 4:47pm UTC](https://discourse.julialang.org/t/ccall-could-not-find-function-in-library-usr-local-cuda-7-0-lib64-libcusolver-so-7-0-28/10009 "2018-03-27T16:47:37Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![cuchxq](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/cuchxq/32/3830_2.png) [@cuchxq](https://discourse.julialang.org/u/cuchxq)\
**Post date:** [March 27, 2018, 4:47pm UTC](https://discourse.julialang.org/t/ccall-could-not-find-function-in-library-usr-local-cuda-7-0-lib64-libcusolver-so-7-0-28/10009/1 "2018-03-27T16:47:38Z")

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Hi everyone, I am trying to use QR factorization to solve linear systems using CuArrays package. I am following [this](http://docs.nvidia.com/cuda/cusolver/index.html#ormqr-example1) CUDA documentation (written in C) and I am trying to do it in Julia.

I am using julia 0.6.0. Here is versioninfo:

```julia
Julia Version 0.6.0
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: Intel(R) Xeon(R) CPU E5-2670 0 @ 2.60GHz
  WORD_SIZE: 64
  BLAS: libopenblas (USE64BITINT NO_AFFINITY NEHALEM)
  LAPACK: libopenblas64_
  LIBM: libopenlibm
  LLVM: libLLVM-3.9.1 (ORCJIT, sandybridge)

```

This is what my function looks like:

```julia
# function to solve linear equations using Cholesky factorization
function solveleq( A::CuArray{Float64,2}, B::CuArray{Float64,2} )
    b = copy(B)
    a = copy(A)
    (a, tau) = CuArrays.CUSOLVER.geqrf!(a)
    CuArrays.CUSOLVER.ormqr!('L', 'T', a, tau, b)
    alpha = Float64(0.0) 
    CuArrays.CUSOLVER.trsm!('L', 'U', 'N', 'N', alpha, a, b)
    return b
end

```

When I call the function, I am having an error `ERROR: LoadError: ccall: could not find function cusolverDnDormqr_bufferSize in library /usr/local/cuda-7.0/lib64/libcusolver.so.7.0.28`.  
Can anyone help me out with this error? Thank you!

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<div class="post-metadata">

**Author:** ![cuchxq](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/cuchxq/32/3830_2.png) [@cuchxq](https://discourse.julialang.org/u/cuchxq)\
**Post date:** [March 28, 2018, 3:49pm UTC](https://discourse.julialang.org/t/ccall-could-not-find-function-in-library-usr-local-cuda-7-0-lib64-libcusolver-so-7-0-28/10009/2 "2018-03-28T15:49:33Z")

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Looks like I have an old version of CUDA. I was using CUDA 7.0. I tried the same code on another machine that has CUDA 9.1 and the error is solved.