Here it goes a simple solution to export a 3D polyline from Matlab to Paraview (a powerful and free 3D viewer). The function takes a list of 3D coordinates and generates an ASCII VTK file with it.
Simple of use, the function has an example in the comments of the header.
David Gingras (2020). Export 3D line to Paraview (https://www.mathworks.com/matlabcentral/fileexchange/22603-export-3d-line-to-paraview), MATLAB Central File Exchange. Retrieved .