summation in matlab help

this is my code to plot summation of 10 normpdf but when i plot figure the plot not like normpdf what the reason ??? plz answer me

w=[0.1139;0.0087;0.6147;0.0437 ; 0.1752;0.0115          ;0.0017;0.0198;0.0034;0.0074   ];
     sigma=[0.0398;0.4716;0.4448;0.2984;0.1466;0.2828;1.3330;0.3010;0.0415;0.3592];
      mu=[0.0074 ;4.9530;0.9306;2.8815;0.5280;4.0052;6.9460;2.4941;0.2566;3.4896];

        x=0:20:80;
        sum=0;
       for i=1:10

       y=w(i)*normpdf(x, mu(i), sigma(i)); 
        sum=sum+y;
      end
       plot(x,sum);
       grid on

[Azzi Abdelmalek]

What are you expecting as result?

[mutah]

my dears this is not the sum values but sum of 10 functions i expected the sum of 10 functions is new function

[Azzi Abdelmalek]

Ok, but that's what your code is doing. If the result is not what you are expecting, then tell us what is the wanted result

[Walter Roberson]

If I understand correctly, you are expecting that normpdf() will return a vector, since you pass in a vector for x.

I do not have that toolbox, so I cannot experiment to be sure, but it does look to me as if it should be returning a vector.

You should put a breakpoint in on the line after you calculate y, run the program, and examine y to see what result you get.

Answer 1

[Image Analyst]

First of all, DON'T use sum as the name of your variable because you'll no longer have access to the built-in function by that name. Call it "theSum" or something else.

Secondly, all you're doing is adding up a bunch of numbers to get a single number out, then you plot it (or try to). What do you expect to see? sum is not an array and does not have different values for different i - it's just a single number, not an array.

[Azzi Abdelmalek]

sum has the same length then x

[Image Analyst]

I think that either y or theSum might want to take an index: y(i) or theSum(i). Or he could just calculate theSum after the loop if he indexes y: theSum = sum(y). Unfortunately I don't have the normpdf() function so I can't really fix the code, plus lack of comments make it unclear what he wants to do.

Answer 2

[mutah]

any body can correct my code or try to plot