Loop for multiple calculation

Hi everyone,

I have a bunch of calculations like this:

F1 = (H(4,1) - baseline1) / baseline1
F2 = (H(20,1) - baseline2) / baseline2
F3 = (H(36,1) - baseline3) / baseline3
...
F20 = (H(308,1) - baseline20) / baseline20

As you can see, the row in H goes up in an increment of 16. I thought a loop may be good for this but am unsure how to go about it. Does anyone have any suggestions?

Thanks,

Le

[Star Strider]

What is baseline?

Scalar?

Vector? What are its dimensions?

[Thang Le]

Baseline is 1x1 double. It's a number I calculated from a preivous step.

[Star Strider]

Are you storing baseline1 and the rest, or are they one-offs?

I ask because you could as easily store them as baseline(1), etc. That would make it much easier for you to reference them in a loop.

Is H a vector (308x1) or matrix?

(I’m doing my best to figure out what you are doing.)

[Thang Le]

I'm sorry my question wasn't clear. I'm not storing baselines. The baselines are just intermediate values that are calculated prior to this. H is a matrix. In this case it's 308x1 but I can see it being 308x8 once I adapt the script to run on multiple region of interests.

[Image Analyst]

OK, I've modified my answer code to take this new information into account.

Answer 1

[Image Analyst]

You can't really have a loop because all your baseline variable have a different name. (Well actually you can but no one wants to show you how because it's not recommended). See the FAQ: http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F

That's why we won't tell you how to make F1, F2, F3, etc. If you want to have F be an array and baseline be an array, then that's normal, and you can use a loop and we will tell you how to do that:

for k = 1 : 20
  hIndex = 4 + (k-1)*16;
  baseline = whatever; % Not sure how you calculate this.
  F(k) = (H(hIndex,1) - baseline) / baseline;
end

Though I don't know why you want the row index of H to go like that.

[Thang Le]

Thank you, Image Analyst! I appreciate your (and everyone's) being patient with me. I'm quite new to working with Matlab as you can tell.