Plotting graph to represent positive/negative roots of polynomial.

Hi,

I have code the calcualtes the roots for a polynomial over the double loop of 2 variables. I'm trying to plot a graph in (L,M) space which indicates at each point ( for 0<L, M<1), via colouring, if both roots are postive, one root being positive or none.

Thanks.

Answer 1

[Samatha Aleti]

As per my understanding you want to plot the points(roots) using different colors according to sign of both the roots. One of the ways do to this is use “scatter” and pass a vector indicating different colors as an input argument to it. Here is the sample code by assuming data x,y:

x = 1:10; 
y = 2:2:20;  
cmap = jet(length(x)); % generates 10 colors (RGB values) 
scatter(x, y, 10, cmap); 

You can define a color vector accordingly and use “scatter” to achieve desired plot.

Refer the following link for more details on ”scatter”:

https://www.mathworks.com/help/matlab/ref/scatter.html?searchHighlight=scatter&s_tid=doc_srchtitle