how can I solve this problem?

Hi,

I have the following set of data:

x=[0;0;0;0;0;1;1;1;1;1;2;2;2;2;2];

y=[0;1;2;3;4;0;1;2;3;4;0;1;2;3;4];

z=[10;11;12;13;14;15;16;17;18;19;20;21;22;23;24];

Now I want to know what the value of y and z if I x=1.

To solve this problem, I have tried to use the function interp2. But I get an error.

Can somebody help me with this?

Thanks :)

Answer 1

[Jacob Wood]

Hi Sharon,

This is a perfect application for Matlab's logical indexing.

x_is_one = x == 1; %find locations where x=1
y_select = y(x_is_one); %pick y where x=1
z_select = z(x_is_one); %pick z where x=1

[Sharon García Herbert]

x=[0.01,3,6,9,12,15,18];

y=[0.6113,0.7577,0.9349,1.1477,1.4022,1.7051,2.0640];

z=[206.136,168.132,137.734,113.386,93.784,77.926,65.038];

scatter3(x,y,z,'filled')

hold on

xlabel('temp')

ylabel('presion')

zlabel('volumen')

hold off

grid minor

x_is_one= x==1; %find locations where x=1

y_select=y(x_is_one); %pick y where x=1

z_select=z(x_is_one); %pick z where x=1

I did that, but I'm not sure if it is right, could you please continue to help me out?

[Jacob Wood]

Hi Sharon,

It doesn't look like X=1 at any point in this example. Would you instead like to interpolate the vectors, and see what y and z would be when x theoretically crosses 1?

x=[0.01,3,6,9,12,15,18];
y=[0.6113,0.7577,0.9349,1.1477,1.4022,1.7051,2.0640];
z=[206.136,168.132,137.734,113.386,93.784,77.926,65.038];
y_select = interp1(x,y,1);
z_select = interp1(x,z,1);

Answer 2

[KSSV]

idx = x ==1 ;
y(idx)
z(idx)