f(x) = (sin(x))^0.5

im trying to plot a graph of y = sqrt(sin(x)) for domain -10<=x<=10 however, im trying to convert my graph from left figure to the figure on the right to exclude all y-values that is non-real. Can anyone advise what must i do to the domain?

below are my attempts:

x2=-10/pi:2pi:10/pi
y=sqrt(sin(x2))
plot(x2,y,'color','blue','linewidth',2)

Answer 1

[Geoff Hayes]

Austin - in your question, you indicate that the domain for x is [-10,10], yet you have

 x2=-10/pi:2*pi:10/pi;

which (when corrected for 2*pi) only returns am array of two elements

 -3.1831       3.1001

of the domain for [-10/pi, 10/pi]. Instead, use linspace to generate a linearly spaced vector/array of elements for your domain. For example,

 x = linspace(-10,10,2000);

will generate 2000 elements that are linearly spaced in the interval [-10,10].

Now you want to only plot those values of y that are real, and ignore those that are complex (with non-zero imaginary components). The latter occur whenever sin(x) is negative. You can ignore these by setting them to NaN as

 y      = sin(x);
 y(y<0) = NaN;

and plot the square root as

 plot(x,sqrt(y),'color','blue','linewidth',2);

Try the above and see what happens!