How to customize a function

Hi, I need to amend my function f_lx.m. Today the function takes 2 parameters; t=age and param_1955=a vector with 3 scalars. I want different parameters to be used depending on age. The function looks like this

function res=f_lx(x,param)

a=param(1);
b=param(2);
c=param(3);

res = zeros(size(x));
ind = x>100;
res(ind) = a+b*exp(c*100)+(x(ind)-100)*0.001;
res(~ind) =a+b*exp(c*x(~ind));
end

Now I have more sets of parameters; param_1938 and param_1945. Given the age x, different parameters will be used - here is a table demonstrating what I mean

x  parameter
65  param_1955
66  param_1955
67  param_1955
68  param_1955
69  param_1955
70  param_1945
71  param_1945
72  param_1945
73  param_1945
74  param_1945
75  param_1945
76  param_1945
77  param_1938
78  param_1938
79  param_1938
...  param_1938
106  param_1938

How can I change my f_lx.m to consider other parameters given age?

[Stephen23]

Numbered parameter names is a sign that you are doing something wrong. You should use indexing to write simpler, more efficient code.

Answer 1

[KSSV]

function res=f_lx(x,param)
a=param(:,1);
b=param(:,2);
c=param(:,3);
res = zeros(size(x));
ind = x>100;
res(ind) = a(ind)+b(ind).*exp(c(ind)*100)+(x(ind)-100)*0.001;
res(~ind) =a(~ind)+b(~ind).*exp(c(~ind).*x(~ind));
end

Your x and param can me arrays now.

[Orongo]

Hi, so I created

param = [param_1938; param_1945; param_1955];
=
2.04021590146881e-10  1.72224144676415e-06  0.123947876025562
0.00463638421048442  4.97805451254727e-07  0.137338003231075
0.00467255690390434  1.90218641756575e-07  0.147616811690677

and get the error

Error in f_lx (line 10)
res(~ind) =a(~ind)+b(~ind).*exp(c(~ind).*x(~ind));

I think is because param is a matrix and not a vector. Just to clarify; age 65-59 take param_1955 (row 1), age 70-76 takes param_1945 (row 2) and age 77-106 takes param 1938 (row 3).

Answer 2

[Orongo]

I have closed this query and raised it here to avoid confusion. https://uk.mathworks.com/matlabcentral/answers/427020-how-to-change-anonymous-function-to-take-array-parameter-and-subject-to-ranges