Index in position 1 is invalid. Array indices must be positive integers or logical values.

I'm trying to make a surface plot but i get the error message where F is a function of x and y but I dont understand what the error message I get means so any help appreciated. Code below error occurs at line 3

function [] = mySurfacePlotter( F,x,y,option)

[X,Y] = meshgrid(x,y);

Z = F(X,Y);

if option == 'surf'

surf(X,Y,Z)

title('Surface');

xlabel('x');

ylabel('y');

else if option == 'contour'

contour(X,Y,Z)

title('Contour');

xlabel('x');

ylabel('y');

end

end

end

[Walter Roberson]

Whatever you are passing in to the first parameter is not a function handle.

Answer 1

[Nishant Gupta]

Like Walter said, the first parameter 'F' need to be a function handle, for eg.

F=@(x,y)(sin(x)+cos(y))

One more thing is, if you select the 'option' as 'contour', it will again give an error. The possible reason for that is the size of the array which you are using to compare is 4 because if you make the slight change as following

else if option == 'cont'

then it will work or you can simply use 'strcmp' function.

[Walter Roberson]

Or r2017a or later,

 option == "surf" 
 option == "contour"