Curve in matlab plotting

How to plot the curve of the below points with the y axis as ln(y) instead of y. So taking the ln values of all y1 and y2 points and then plotting. Also need to indicate the points on the curve.

X	 Y1	     Y2
57	 78.2	165.1
87	 67.06	101.8
107	 64.66	88.7
257	 61.43	63.58
507	 61.45	61.47
1007 60.51	60.91

Answer 1

[Riccardo Scorretti]

Dear Amy,

if I understand correctly your question, you can use semilogy instead of plot:

data =  [ ...
    57	 78.2	165.1 ; ...
    87	 67.06	101.8 ; ...
    107	 64.66	88.7  ; ...
    257	 61.43	63.58 ; ...
    507	 61.45	61.47 ; ...
    1007 60.51	60.91 ];
x = data(:,1) ; y1 = data(:,2) ; y2 = data(:,3);

% Here we go ...
figure
semilogy(x, y1, 'o-', x, y2, 's-');
grid on ; legend('y1', 'y2');
xlabel('x') ; ylabel('y');

[Amy Topaz]

Thank you.

The y axis is ln(y) and not log base 10 y. How to do that?

[Riccardo Scorretti]

Well, in this case I'm afraid you have to to "by hand", but the grid will not be that nice:

data =  [ ...
    57	 78.2	165.1 ; ...
    87	 67.06	101.8 ; ...
    107	 64.66	88.7  ; ...
    257	 61.43	63.58 ; ...
    507	 61.45	61.47 ; ...
    1007 60.51	60.91 ];
x = data(:,1) ; y1 = data(:,2) ; y2 = data(:,3);
% Here we go ...
figure
plot(x, log10(y1), 'o-', x, log10(y2), 's-');
grid on ; legend('y1', 'y2');
xlabel('x') ; ylabel('log(y)');