how to plot curved fitting but the value of x and y must be key in by the user at the command window.

this is the programing that i had done and the output that i want.

 x=[249 191 150 139 130 123]';
 y=[20 40 60 80 100 120]';
cftool(x,y);

fitresult = fit(x,y,'exp2'); figure; subplot(111), plot(fitresult,x,y); xlabel('distance(pixels)') ; ylabel('molecular weight(mer)');grid;

my problem is,the value x and y must be key in at the command window. so i write another program.this my program..

x= input ('x? '); y=input ('y? ');

cftool(x,y);

fitresult = fit(x,y,'exp2'); figure; subplot(111), plot(fitresult,x,y); xlabel('distance(pixels)') ; ylabel('molecular weight(mer)');grid;

 but when i key in the value x and y at the command window,i cannot get the output. can u help me to solve this problem.

Answer 1

[Geoff]

Do you mean that you are experiencing this:

> x = input('x? ')
x? 249 191 150 139 130 123
 249 191 150 139 130 123
    |
Error: Unexpected MATLAB expression.

Unless you tell it not to, the input command evaluates what you type in as a MatLab expression. You could do this:

> x = input('x? ', 's')
x? [249 191 150 139 130 123]

x =

[249 191 150 139 130 123]

But I would never do that, even if I am the only one who would use the program. I don't like programs that can execute arbitrary commands typed in by the user. Instead, I would read the input as a string and then extract the numbers from it as follows:

> x = sscanf( input('x? ', 's'), '%d' )
x? 249 191 150 139 130 123

x =

     249
     191
     150
     139
     130
     123

The above code only accepts integers. If you wanted to allow doubles, use the '%f' format instead:

x = sscanf( input('x? ', 's'), '%f' );