CODEWITHSUNDEEP
matlab
ZK Zhao
ZK Zhao

Reputation: 21583

Matlab: How to construct a series of constants? And How to reuse them?

I have a set of constants

case 'a'
  h_grad = 300;h_alpha = 0.11;
case 'b'
  h_grad = 350;h_alpha = 0.15;
case 'c'
  h_grad = 450;h_alpha = 0.22;
case 'd'
  h_grad = 550;h_alpha = 0.3;

How can I construct them, so I can use them like a.h_grad, a.h_alpha, or b.h_grad, b.h_alph. ?

And I may want to use these data like:

v = custom_function(a)
% surface_type could be a, b, c or d
  function v = custom_function(surface_type)
    h_grad = surface_type.h_grad;
    h_alpha = surface_type.h_alpha;
    v = h_grad^h_alpha
  end

And, since a/b/c/d may be used in other cases for other variable, how can I put these predefined a.h_grad constant into another object? So they wont pollute the who program. For example, I may re-use them like My_Constant_Containter.a.h_grad?

Upvotes: 1

Views: 63

Answers (2)

Divakar
Divakar

Reputation: 221684

You can use deal (Distribute inputs to outputs) here -

%// Define arrays to hold the scalars
h_grad_vals = [300 350 450 550];  
h_alpha_vals = [0.11 0.15 0.22 0.3];

h1 = num2cell(h_grad_vals)
[a.h_grad,b.h_grad,c.h_grad,d.h_grad] = deal(h1{:})

h2 = num2cell(h_alpha_vals)
[a.h_alpha,b.h_alpha,c.h_alpha,d.h_alpha] = deal(h2{:})

Output -

a = 
     h_grad: 300
    h_alpha: 0.1100
b = 
     h_grad: 350
    h_alpha: 0.1500
c = 
     h_grad: 450
    h_alpha: 0.2200
d = 
     h_grad: 550
    h_alpha: 0.3000

Suggestion

Rather than saving to four different structs, for easy portability of codes and code maintenance, it would make more sense to have these scalars stored as struct of arrays. So, you can do this -

A.h_grad = h_grad_vals %// h_grad_vals from earlier code
A.h_alpha = h_alpha_vals %// h_alpha_vals from earlier code

Thus, you would be get -

A = 
     h_grad: [300 350 450 550]
    h_alpha: [0.1100 0.1500 0.2200 0.3000]

Leaving you with just one variable A and thus, a much cleaner workspace!

Edit

Here's a fix to solve the question based on the new info provided in the Edit section -

A = cat(1,a,b,c,d);
fns = {'a','b','c','d'};
for k = 1:numel(fns)
    My_Constant_Containter.(char(fns(k))) = A(k);
end

Here's the data store in the output struct looks like -

>> My_Constant_Containter.a
ans = 
     h_grad: 300
    h_alpha: 0.1100
>> My_Constant_Containter.b
ans = 
     h_grad: 350
    h_alpha: 0.1500
>> My_Constant_Containter.c
ans = 
     h_grad: 450
    h_alpha: 0.2200
>> My_Constant_Containter.d
ans = 
     h_grad: 550
    h_alpha: 0.3000

Upvotes: 2

rozsasarpi
rozsasarpi

Reputation: 1641

Are you looking for something like this:

a.h_grad = 300;a.h_alpha = 0.11;
b.h_grad = 350;b.h_alpha = 0.15;
c.h_grad = 450;c.h_alpha = 0.22;
d.h_grad = 550;d.h_alpha = 0.3;

They are called structure type variables. The case words are not clear to me, are you using switch?

EDIT: Based on the new info you provided, one possibility if you want to keep the structure variables (CC-constant container):

CC.a.h_grad = 300;CC.a.h_alpha = 0.11;
CC.b.h_grad = 350;CC.b.h_alpha = 0.15;
CC.c.h_grad = 450;CC.c.h_alpha = 0.22;
CC.d.h_grad = 550;CC.d.h_alpha = 0.3;

surface_type = 'b';

function v = custom_function(surface_type)
    h_grad_i  = CC.(surface_type).h_grad;
    h_alpha_i = CC.(surface_type).h_alpha;
    v         = h_grad_i^h_alpha_i;
end

Upvotes: 2

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