How to diffuse with gradient matrix

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In GAMA's manual, I observed that diffusion can be performed by customizing uniform/irregular gradient matrices, as shown in the figure.


But I couldn't find any code that can use gradient matrix to perform diffusion, and when I wrote code it like this:

diffuse var: phero on: cells matrix:mat_grad propagation:gradient;

an error occurred:""matrix:" and "propagation:" can not be used at the same time".

Does this mean that gradient diffusion cannot be performed based on a custom matrix, and can only be executed using parameters such as variation and radius? However, my project requires irregular gradient diffusion, and diffusion based on parameters cannot achieve the same effect.

So, is there anyone who can help me?

1. If gradient diffusion can be performed based on a gradient matrix, please provide the correct execution code.
2. If it is not possible, how can I achieve the effect of my irregular gradient diffusion?

Thank you very much!!!