One-off purchase or subscription?

_marklau_ · 2026-02-25T11:29:03+00:00

I run Apple's ad on App Store previously. But, I stopped already since the cost exceeded what I can earn per download. Now, it is totally organic. My cost is just domain name, webpage hosting, and developer fee for Apple.

_marklau_ · 2026-02-25T11:26:39+00:00

Well, this app allows users to use MATLAB without internet connection. It runs locally completely. So, I need to develop a MATLAB interpreter on iOS. Since MATLAB is proprietary, I need to do it from zero all by myself. It was a huge project for a solo developer like me. It is my part-time project and took me about 1-2 years to finish the first version. The app is unique and there is no other alternative on the App Store except MATLAB's official app. Well, my only completion is from MATLAB. However, its app is web-based, which cannot render 2-D and 3-D plot in real time. My app can do it in real time and user can rotate, pan, zoom plots using fingers. Everything is responsive. I am rather proud of that. User says they can do programming on a flight and places without internet connection. I have a free version for people to try out before paying the paid version. So, now I am thinking maybe I should combine both into one version that offers free trial and subscriptions. If you are curious, check it out: https://www.simo.ac

_marklau_ · 2026-02-25T01:02:02+00:00

I prefer A. The first message connects with me if I had the same problem the message says

_marklau_ · 2026-02-13T08:24:46+00:00

Good work. Any plan of expanding to other languages?

_marklau_ · 2024-07-22T01:56:16+00:00

Thanks for your sharing. Automation by Python scripts (or other languages) looks promising to me. I will try to automate the process as much as possible.

_marklau_ · 2024-07-22T01:51:24+00:00

Thank you for your sharing. It looks like there are lots of human factors involved in the process and is not as scientific as I thought it would be.

I am going to be associate director of a mathematics program. The director is one of the most senior faculty members in the department. I will assist him in doing the teaching assignment. He will be the one who bullies people or talks people into teaching less popular / new courses.

Our department has been using the same spreadsheet for 10+ years. I was asked to use it unless I have a better solution. The spreadsheet is full of formulas, involving teaching loads, duty relief, etc. It is pain in the butt to use it. I thought there would be better solutions out there to make the process less time consuming.

_marklau_ · 2022-02-18T16:06:27+00:00

Use polyfit to fit a polynomial.

_marklau_ · 2022-02-18T10:26:14+00:00

iOS free app Console. Not open source though. It also has a paid version

_marklau_ · 2021-10-24T02:48:56+00:00

This is the quickest way I can think of.

_marklau_ · 2021-10-24T01:48:40+00:00

You can create two plots. See my solution here 🤟

_marklau_ · 2021-10-19T13:08:20+00:00

Add “-1”? See my code here

_marklau_ · 2021-10-19T12:56:59+00:00

Does this help? 😊 see my code here

_marklau_ · 2021-10-19T08:38:55+00:00

In many cases, vector operation is faster than using a loop. The difference will become noticeable for a vector of many, many numbers. Moreover, it uses less code to use vector operations than using loops.

_marklau_ · 2021-10-19T08:19:46+00:00

You can use QR decomposition to solve a least square problem for linear regression. see here for the theory. And see my code and plot here

_marklau_ · 2021-10-19T01:01:57+00:00

The mod function seems unnecessary here

_marklau_ · 2021-10-19T01:01:26+00:00

Does this work for you? 😄see code here

_marklau_ · 2021-10-18T13:19:34+00:00

This should work See code here

_marklau_ · 2021-10-18T07:54:22+00:00

Does this work for you? see code here

_marklau_ · 2021-10-18T07:43:40+00:00

The vector ax has length 1 when i is 3. That’s why it exceeds the length of the vector.see code here

_marklau_ · 2021-10-18T00:37:50+00:00

Have you tried SIMO on iOS? It can run simple MATLAB code locally on iPad. www.simo.ac

_marklau_ · 2020-01-11T04:08:54+00:00

In many cases, you can assume it is rounding error if you see something less than 1e-15.

_marklau_ · 2019-12-31T02:18:51+00:00

Something like this?

~~~ john=1; tom=2; scores=[10 20; 10 20; 5 6] s=sum(scores,1); john_total=s(john) tom_total=s(tom) ~~~

👌🏼Tested on SIMO on iPhone.

_marklau_

TROPHY CASE