Canvas with static content and items

Question

I have a Canvas which contains static elements - those elements use binding to draw it in the right places. Now I need to draw other elements depending on items in a collection. I want to use ItemsControl, but I don't know how to do it correctly. My current pseudo-code:

<UserControl.Resources>
    <RectangleGeometry x:Key="MyGeometry1">
        <RectangleGeometry.Rect>
            <MultiBinding Converter="{StaticResource RectConverter}">
                <Binding Path="ActualWidth" ElementName="m_Canvas" />
                <Binding Path="ActualHeight" ElementName="m_Canvas" />
            </MultiBinding>
        </RectangleGeometry.Rect>
    </RectangleGeometry>
</UserControl.Resources>

<Canvas x:Name="m_Canvas">
    <!-- "static" content -->
    <Line x:Name="Line1" X1="{Binding Line1X1}" X2="{Binding Line1X2}" Y1="{Binding Line1Y1}" Y2="{Binding Line1Y2}"/>
    <Line X1="0" X2="{Binding ActualWidth, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Canvas}}}" Y1="0" Y2="0">
    <Path Fill="#35A500"
          Opacity="0.15">
        <Path.Data>
            <GeometryGroup FillRule="EvenOdd">
                <StaticResource ResourceKey="MyGeometry1" />
            </GeometryGroup>
        </Path.Data>
    </Path>
    
    <Line X1="{Binding Items[0].X1}" X2="{Binding Items[0].X2}" Y1="{Binding Items[0].Y1}" Y2="{Binding Items[0].Y2}"/>
    <Line X1="{Binding Items[1].X1}" X2="{Binding Items[1].X2}" Y1="{Binding Items[1].Y1}" Y2="{Binding Items[1].Y2}"/>
    <Line X1="{Binding Items[2].X1}" X2="{Binding Items[2].X2}" Y1="{Binding Items[2].Y1}" Y2="{Binding Items[2].Y2}"/>
</Canvas>

I tried something like this:

<ItemsControl ItemsSource="{Binding Items}">
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <Canvas>
                <!-- "static" content -->
                <Line x:Name="Line1" X1="{Binding Line1X1}" X2="{Binding Line1X2}" Y1="{Binding Line1Y1}" Y2="{Binding Line1Y2}"/>
                <Line X1="0" X2="{Binding ActualWidth, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Canvas}}}" Y1="0" Y2="0">
            </Canvas>
        </ItemsPanelTemplate>
<!-- (...) other code -->
</ItemsControl>

But I have an error:

Error XDG0062 Cannot explicitly modify Children collection of Panel used as ItemsPanel for ItemsControl. ItemsControl generates child elements for Panel.

I understand that is because I put Line1 inside Canvas but how to make such Canvas with some kind static content and also as a container for items?

Answer 1

Nd4j does not support complex ndarrays anymore. We did at one point but a lot of our ops did not directly support it. If you want to use FFTs with nd4j you'll have to do some sort of an approxmation or use a different library and convert you nd4j array to a toDoubleMatrix()/toDoubleVector() and back.

Note that this will of course cause some performance penalties including copying data and a bit of memory overhead if you choose to go the copy route.

Apologies for the confusion there but hopefully that clears up why you don't see as many docs on it.

For the in memory representation a complex ndarray is usually just the components laid out as: real, imaginary, real, imaginary

in the in memory buffer. Nothing would stop you from creating that as well.