± use in MATLAB

CL = (0.331±0.008) + (0.15±0.002)*ALPHA

I have to code this equation in MATLAB but don't know, how can I code this?

Thanks!

Answer 1

[Star Strider]

One option:

CL = [(0.331+0.008) + (0.15+0.002)*ALPHA 
      (0.331-0.008) + (0.15-0.002)*ALPHA]; 

Experiment to get different results, depending on how you want to define the equations.

[Les Beckham]

Shouldn't there be four elements (for the four combinations (++, +-, -+, --)?

[Star Strider]

There can be. It depends on the desired result.

I kept it simple here to demonstrate the correct approach.

[Priyank Goel]

Thanks for the answer,

Is there any other way as writing the complete equation 4 times can be little tedious?

[Star Strider]

It’s quite possible to make this ridiculously complicated.

The easiest option is likely:

CL = [0.331 0.15] + [0.008 0.002].*[1 1; 1 -1; -1 1; -1 -1];

and just let it go at that.

EDIT — (27 Feb 2021 at 22:04)

Those are obviously only the limits, according to whatever criteria you wish to apply to them. Use them appropriately in your code.

Answer 2

[Walter Roberson]

syms ALPHA
syms delta_1 delta_2
assume(-0.008 <= delta_1 & delta_1 <= 0.008)
assume(-0.002 <= delta_2 & delta_2 <= 0.002)
CL = 0.331 + delta_1 + (0.15+delta_2)*ALPHA 

CL = 

expand(CL)

ans = 

The matrix approach is not correct, as it gives specific values, whereas you need a range of values. For example you might have 1/(CL-0.15*ALPHA-0.331) as part of an expression, and if you only work with the edge cases you miss the fact that this passes through 1/0 .