Utilising matlab plots to find constants

Finding m and c for an equation y = mx + c, with the help of math and plots.

In this case, y is data_model_1, x is time

Avoid other matlab functions like fitlm as it defeats the purpose.

I am having trouble finding the constants m and c. I am trying to find both m and c by limiting them to a range (Based on smart guess) and I need to deduce the m and c values based on the mean error range. The point where mean error range is closest to 0 should be my m and c values.

load(file)

figure

plot(time,data_model_1,'bo')

hold on

for a = 0.11:0.01:0.13
    c = -13:0.1:-10

      data_a = a * time + c ;

      plot(time,data_a,'r');

end

figure
hold on

for a = 0.11:0.01:0.13
    c = -13:0.1:-10

      data_a = a * time + c ;

      mean_range = mean(abs(data_a - data_model_1));

      plot(a,mean_range,'b.')

   end

EDIT: I have attached an example with the file "fil"

[Jan]

What exactly is your question? There are much better methods to determine the line equation numerically. Maybe you should not use polyfit, but the underlying formula is such easy, that you can implement it by your own.

[Madlab]

How to find the constants m and c with the help of plots?

I know there are other methods but I need to use mathematics and plots to solve for m and c, nothing else. There is no polyfit function anywhere in my code either.

[Jan]

While there is no polyfit in your code, it is easy to determine the constants m and c using maths instead of plots.

Again: What is the problem with the code you have posted?