# How do I plot points coming from a for loop without using vectors?

1 view (last 30 days)
Hi, I am new to Matlab so excuse my ignorance. I am trying to make a code that evaluates a definite integral from 0 to infinity for different values of two parameters, which I called v,L in the script below. Then I want to plot these definite integrals versus values of, say, L, which increases by one in each cycle. Why aren't values of L on the horizontal axis equally spaced as they should be? Is there something wrong with the plot function? If so, is there a way to plot points coming from a for loop as they get out, without using vectors? Thanks in advance.
syms x;
double L;
double v;
f=L*exp(-v*x^2);
L=0;
v=1;
for i=0:50
L=L+i;
k=int(f,x,0,inf);
plot(L,k,'o');
hold on
end
hold off
I think what Stephen refers to is that
double L; % = double('L')
doesn't declare a variable (as in other languages), but type-casts the character 'L' to type double, which is simply the number 76.

Hi,
values on the x-axis are not equally spaced because on every interation you increase L by i, which itself is increased by 1 on every interation:
1st interation: L = 0+0 = 0
2nd L = 0+1 = 1
3rd L = 1+2 = 3
4th L = 3+3 = 6
...
but you can just use i as your x-parameter for the plot function:
plot(i,k,'o');
> "is there a way to plot points coming from a for loop as they get out, without using vectors?"
you allready do that using hold on
Thank you! This solved my issue. integral() is numeric and int() is symbolic then, I will keep in mind

R2021a

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!