Vectorized parametric step function

I have implemented a parametric step function using object orientation and vectorization code but there is an inconstancy in some results. The code is as follows:

classdef A6

properties

eps

end

methods

function Y = value(obj,X)

Y=double(((X>=0) & (X<0.3)))...

+double((X>=0.3) & (X<0.4)).*obj.eps...

+double((X>=0.4) & (X<0.6))...

+double((X>=0.6) & (X<0.7)).*obj.eps...

+double((X>=0.7) & (X<=1));

end

end

end

I tested the function using, eps=0.8, dx=1/20 and X=(dx:dx:1-dx). When calculating Y=value(a,X), X(12)=0.6 but Y(12)=1 when I should expect the result to be 0.8 according to the previous inequalities. Any help will be appreciated. Thanks.

Answer 1

[Abolfazl Chaman Motlagh]

it is not about your code.

i test it here :

X = 0.05:0.05:1-0.05

X = 1×19

0.0500 0.1000 0.1500 0.2000 0.2500 0.3000 0.3500 0.4000 0.4500 0.5000 0.5500 0.6000 0.6500 0.7000 0.7500 0.8000 0.8500 0.9000 0.9500

X(12)

ans = 0.6000

X(12)<0.6

ans = logical
   1

this result is wrong.

because :

X(12) - 0.6

ans = -1.1102e-16

so the way you create the X have a small telorance.

do this :

X = round( (0.05:0.05:1-0.05) * 100) / 100 ;
Y=double(((X>=0) & (X<0.3)))...
             +double((X>=0.3) & (X<0.4)).*0.8...
             +double((X>=0.4) & (X<0.6))...
             +double((X>=0.6) & (X<0.7)).*0.8...
             +double((X>=0.7) & (X<=1));
plot(X,Y)

Y(X==0.6)

ans = 0.8000

-----------------------------------------------

it is strange because if you use linspace function, other part of code goes wrong:

X = linspace(0.05,1-0.05,19)

X = 1×19

0.0500 0.1000 0.1500 0.2000 0.2500 0.3000 0.3500 0.4000 0.4500 0.5000 0.5500 0.6000 0.6500 0.7000 0.7500 0.8000 0.8500 0.9000 0.9500

Y = double(((X>=0) & (X<0.3)))...
             +double((X>=0.3) & (X<0.4)).*0.8...
             +double((X>=0.4) & (X<0.6))...
             +double((X>=0.6) & (X<0.7)).*0.8...
             +double((X>=0.7) & (X<=1));
plot(X,Y)

X(8) , Y(8)

ans = 0.4000

ans = 0.8000

which is wrong, it should be 1.

i think it's error in the way matlab create vectors.

[Pablo C.]

Thank you very much!