update README.md.

Signed-off-by: 刘明宏 <liuminghong@mail.sdu.edu.cn>

README.md

@@ -20,24 +20,38 @@ GeoMesh
 For 3D geological modeling and mesh generation, GeoMesh is used. This is an open-source tool specifically designed for electromagnetic (EM) modeling, based on the COMSOL Multiphysics and MATLAB interface (Liu et al., 2024). GeoMesh generates unstructured tetrahedral meshes, which are ideal for representing complex subsurface structures in the forward modeling process. You can find the tool at https://gitee.com/sduem/geomesh
 
 Additionally, em3d-MT supports two types of direct solvers for solving the finite element system:
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 Panua-Pardiso:
 An optimized direct solver used for solving large sparse linear systems. It offers high performance and memory efficiency. More information can be found at https://panua.ch/pardiso/
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 UMFPACK: 
 An alternative direct solver supported by em3d-MT for solving sparse linear systems, suitable for small models or testing. More information can be found at http://faculty.cse.tamu.edu/davis/suitesparse.html
 
 #### 2.3 Installation
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 Step 1: Install MATLAB
 Install MATLAB (R2023a or later). Parallel Computing Toolbox is available for multi-core support.
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 Step 2: Set Up Panua-Pardiso Solver 
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 Windows: Refer to Barbara (2025). Add PARDISO lib to Matlab in Windows and LINUX, MATLAB Central File Exchange. https://www.mathworks.com/matlabcentral/fileexchange/119053-add-pardiso-lib-to-matlab-in-windows-and-linux, January 13, 2025.
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 The following steps outline how to configure the Panua-Pardiso solver in the Windows environment:
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 [1]	Register for a Panua account. Then download the panua-pardiso-20240228-win package from the official website: https://panua.ch/pardiso/, and extract the contents.
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 [2]	Open the bin folder in the extracted directory. Press Win + R, type cmd, and drag get_fingerprint.exe into the Command Prompt window. Press Enter to generate your machine fingerprint.
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 [3]	Copy the machine fingerprint into the input box on the Panua Pardiso website. An activation key will be sent to your registered email.
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 [4]	Create a file named panua.lic, paste the activation key into the file, and move it to the user directory (e.g., C:\Users\Username).
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 [5]	Add MinGW Compiler to MATLAB by visiting: https://www.mathworks.com/matlabcentral/fileexchange/52848-matlab-support-for-mingw-w64-c-c-compiler
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 [6]	Download and install Intel OneAPI Base Toolkit including MKL (Math Kernel Library) from: https://www.intel.com/content/www/us/en/developer/tools/oneapi/onemkl.html
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 [7]	Compile MEX Files. After updating the specific paths in the runMEM.m script to match your system, run the script in MATLAB to compile the required .mex files.
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 The following script is used to compile the Panua-Pardiso interface with MATLAB via MEX. It links the necessary Panua, MATLAB, and Intel MKL libraries using MinGW:
 
 %% This one works (pardisoinit):