Moving from an index in the matrix to an x,y value

Hey

I have a 50x50 matrix that indicates points on the X,Y axis

I have some kind of function that holds the index that indicates a row and a column of some point.

My question is how do I go from an index to get the real value on the X axis and Y axis?

Let's say the indexes I got are:

row_idx=43, col_idx=3

Can I say that the value of the point is (3,7)? Or should we add 1+ to the y value? I got confused..

Thank you

[the cyclist]

I got confused, too.

Maybe you could post a much smaller example (say, 5x5) of your matrix. Then, what is your input, and what should the output be?

Answer 1

[Star Strider]

Perhaps something like this —

x = linspace(0, 10, 50);
y = linspace(0, 10, 50);
zm = exp(-(x-4.5).^2/4) .* exp(-(y(:)-4.5).^2/4);

[xm,ym]  = ndgrid(x,y);
Zfcn = scatteredInterpolant(xm(:),ym(:),zm(:));

row_idx = 43;
col_idx =  3;
xq = interp1(x, row_idx)

xq = 8.5714

yq = interp1(y, col_idx)

yq = 0.4082

zi = Zfcn(xq,yq);

figure
surf(xm, ym, zm)
hold on
plot3(xq, yq, zi, 'rp', 'MarkerFaceColor','r', 'MarkerSize',15)
hold off
grid on
xlabel('x')
ylabel('y')
zlabel('z')

[az,el] = view

az = -37.5000

el = 30

% view(210,el)

.