Create a MATLAB script that generates x-values from -3 to 3 using linspace with 150 plot value. Define three different y-values as follows:

1. y1=tan(x)
2. y2=1/sqrt(x^2+1)
3. y3=1/(1+e^x)

Plot these three curves on the same graph using different line styles and colors. Add appropriate labels for the x-axis and y-axis, a title for the plot, and a legend.