How to create generic code with DenseMatrix?

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Andrey Ilinykh

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Sep 15, 2017, 12:50:31 AM9/15/17
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Hello everybody!
I have very simple problem. I want to create generic code which should operate with different matrix type - mostly DenseMatrix[Double] or DenseMatrix[Float]. Something like this:

class MyClass[T](a: DenseMatrix[T], b: DenseMatrix[T]) {
def myfunc = {
  a * b
}
//more methods here ...

}


and later use as 
  new MyClass[Float](a, b) 
or
 new MyClass[Double](a, b)

but it doesn't compile. The error I got is

Error:(87, 9) diverging implicit expansion for type breeze.linalg.operators.OpMulMatrix.Impl2[breeze.linalg.DenseMatrix[T],breeze.linalg.DenseMatrix[T],That]
starting with method opMulMatrixFromSemiring in object OpMulMatrix
      a * b

What would be the right way to do it?

Thank you,
  Andrey

David Hall

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Sep 15, 2017, 2:17:57 PM9/15/17
to scala-...@googlegroups.com
In Breeze, operations are provided via an implicit parameter that provides the implementation. This allows for a lot more flexibility and extensibility in terms of how things are put together. This is provided via the UFunc abstraction (https://github.com/scalanlp/breeze/wiki/Universal-Functions) 


More concretely, you need class MyClass[T](a: DenseMatrix[T], b: DenseMatrix[T])(implicit mul: OpMulMatrix.Impl2[DenseMatrix[T], DenseMatrix[T], DenseMatrix[T]])

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Andrey Ilinykh

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Sep 15, 2017, 7:26:03 PM9/15/17
to Scala Breeze
Cool. It works. Thank you!


On Friday, September 15, 2017 at 11:17:57 AM UTC-7, David Hall wrote:
In Breeze, operations are provided via an implicit parameter that provides the implementation. This allows for a lot more flexibility and extensibility in terms of how things are put together. This is provided via the UFunc abstraction (https://github.com/scalanlp/breeze/wiki/Universal-Functions) 


More concretely, you need class MyClass[T](a: DenseMatrix[T], b: DenseMatrix[T])(implicit mul: OpMulMatrix.Impl2[DenseMatrix[T], DenseMatrix[T], DenseMatrix[T]])
On Thu, Sep 14, 2017 at 9:36 PM, Andrey Ilinykh <aili...@gmail.com> wrote:
Hello everybody!
I have very simple problem. I want to create generic code which should operate with different matrix type - mostly DenseMatrix[Double] or DenseMatrix[Float]. Something like this:

class MyClass[T](a: DenseMatrix[T], b: DenseMatrix[T]) {
def myfunc = {
  a * b
}
//more methods here ...

}


and later use as 
  new MyClass[Float](a, b) 
or
 new MyClass[Double](a, b)

but it doesn't compile. The error I got is

Error:(87, 9) diverging implicit expansion for type breeze.linalg.operators.OpMulMatrix.Impl2[breeze.linalg.DenseMatrix[T],breeze.linalg.DenseMatrix[T],That]
starting with method opMulMatrixFromSemiring in object OpMulMatrix
      a * b

What would be the right way to do it?

Thank you,
  Andrey

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