How can I write the MATLAB code f(x) = x + 5 for 0<x<10?

The following code did not solve the problem.

if ((0 < x) | (x < 100)) y = x + 5 end

Answer 1

[Walter Roberson]

You cannot define that in MATLAB: it is not possible to define a function that has no definition over a particular range of arguments. You can define a function that is NaN outside a range, or 0, but you have to give it some meaning. Either that or never call the function with parameters outside the defined range.

[Sam]

ok

Answer 2

[sixwwwwww]

There is a work around to this problem using symbols in MATLAB as follows:

Suppose your x value lies over range from -100 to 100 and for range 0 to 10 you need y = x + 5, then you can do as follows:

syms x_sym y_sym
for x = -100:1:100
    if (x > 0 && x < 10)
        y_sym = x_sym + 5;
        % Other processing as desired. Also result can be back converted from symbol type to
        % double number type as 
        % y = double(subs(y_sym, x_sym, x));
    end
end

I hope it will help you a little

[Sam]

Thanks!

[Sam]

The program as written results in a plot with one number, 10. How can the code be modified to produce a range of numbers along the x axis between but not including digits 0 and 10?

[sixwwwwww]

In this case the code can be written in the following form:

syms x_sym y_sym
count = 1;
for x = -100:1:100
    if (x > 0 && x < 10)
        y_sym = x_sym + 5;
        y_range(count) = double(subs(y_sym, x_sym, x));
        x_range(count) = x;
        count = count + 1;
    end
end
disp('x values between 0 and 10')
disp(x_range)
disp('Values for function y = x + 5 given x values')
disp(y_range)

[summyia qamar]

what is the purpose of count here?

[Walter Roberson]

count is acting as an index into the vector being constructed. You do not know ahead of time how many values will match.

Answer 3

[Big Wolf]

Write a MATLAB program to find the value of y when y=|x| when x<5 and y=5x when 5<or = x <10

[Walter Roberson]

If x<5 but also 5<or=x<10 then x<5 but also 5<=x which is x >= 5. There is, however, not number which is simultaneously less than 5 and >= 5. Therefore the problem is impossible.

Answer 4

[abod]

if r=10 and the i increased from 0 to 10 with increments of 2 and v=i*r

[Walter Roberson]

r = 10;
i = 0 : 2 : 10;
v = i .* r

v = 1×6

0 20 40 60 80 100