If it is truly "we can do X just like FamousApplication(tm), except we are in the browser and we can be profitable charging 10% as much as FamousApplication(tm)", that is pretty compelling. That is not something that is really difficult to sell if you can truly deliver and be profitable at that price point.
I am not sure how it is possible you can replace a computationally expensive client side application like MatLAB with something that runs in the cloud, without discovering order of magnitude more efficient solutions for a wide array of well know mathematical algorithms. If you have discovered such then you can pretty much write your own check, if not there is no way you can scale as a service. Thats what I would think you have to convince potential investors about.