How to write a program to draw a triangle of stars in MATLAB?

I have a exam and don't know how to write a program to draw a triangle of stars, for example :

       *
       **
       ***
       ****
       *****
And also flip upside down, for example :

            *
           **
          ***
         ****
        *****
And also in the form of isosceles triangle, for example :

             *
            ***
           *****
          *******
And also in the form of a specific, for example :

             *
            ***
           *****
          *******
           *****
            ***
             *

Please help me!

[Mohammad Hamza]

 fprintf('    *\n   ***\n  *****\n *******\n*********\n')

[Stephen23]

@Mohammad Hamza: your comment made me laugh. Good work.

I am not sure why so many of the answers rely on nested loops and stacks of ifs. MATLAB code should be beautiful, not written like ugly C++. Like this:

>> char(32+10*tril(ones(5)))
ans =
*
**
***
****
*****

[rohit kumar]

For r=1:4 Forc=1:r fprintf('*'); end fprintf('\n) end

Answer 1

[Image Analyst]

Hint:

string = '     '; % 5 spaces.
index1 = 2;
index2 = 4;
string(index1:index2) = '*';
fprintf('%s\n', string);

You need to figure out what index1 and index2 are for the various lines you want to print out.

[Ali Salim]

Thank you for your answer but my teacher wants such a solution :

 clc
 clear all
 close all
n=input('Enter n=');
for i=1:n;
for j=1:j-1
fprintf('*');
fprintf('');
end
fprintf('\n');
end

The solution for :

       *
       **
       ***
       ****
       *****

But I want the solution to the rest of the triangles

[Image Analyst]

Shouldn't be too hard. There are a variety of ways to do it. I showed you one. You just need to figure out what index1 and index2 are as a function of i, since they will be different for each value of i. For example, for the first one, index1 is always 1 and index2 equals i.

[Ali Salim]

Thank you (Image Analyst)

[Kunal Kabi]

The program is little bit incorrect . The correct program is:

clc;

clear all;

close all;

n=input('Enter n=');

for i=2:n

for j=1:i-1

fprintf('*');

fprintf('');

end

fprintf('\n');

end

[Jorge Rocha]

But how can I make the third one? (equilateral).

Answer 2

[Konstantinos Sofos]

Hi,

For the first

x = [];
for i = 1 : 5
    x = strcat(x,'*');
    disp(x)
end

for the second

x = [];
for i = 1 : 5
    x = strcat(x,'*');
    s = [blanks(5-i) x];
    disp(s)
end

for the third, the pyramid

x = [];
for i = 1 : 5
    x = strcat(x,'*');
    s = [blanks(5-i) x];
    disp([s fliplr(s)])
end

[Image Analyst]

Ali, normally we don't just do your exam questions for you 100%, lest you instructor finds out and you get in trouble.

[Ali Salim]

 oh!  Please..Please

[Ali Salim]

Thank you (Konstantinos Sofos) for your answer

[Dan Po]

what is the 'x=[]' for? i tried looking this up and dont know what to search for. right now i am trying to use a for loop to do the same thing, but with symmetry.

   x = [];
for i = 1 : 5
    x = strcat(x,'*');
    s = [blanks(5-i) x];
    disp([s fliplr(s)])
end

   my code is this, i want to make it shorter:
row=input('enter number: \n');
y=rem(row,2);
if y==0 ;
%     fprintf(2,'ERROR: you entered an even number\n')
    error('ERROR: %.2f an even number\n',row)
else    y>0
for i= 1:row;
     for j=1:row-i
       fprintf(' ')
     end
     for k=1:2*i-1
       fprintf('*')
     end
    fprintf('\n') 
end  
for j=row-1:-1:1
    for q=1:row-j
       fprintf(' ')
     end
    for         k=2*j-1:-1:1
       fprintf('*')
    end
     fprintf('\n') 
end
end

[Image Analyst]

It's to make an x that you can append to. If you don't do that in advance, then what happens when it gets to this line:

x = strcat(x,'*');

It needs to take an already existing x and add a * to it. But if you didn't assign null to x, there is no x to add a star to. So even though x is initialized to null, it's really still there, and we can append stuff to it.

Answer 3

[Kunal Kabi]

For printing in this order

*****

***

**

*

Use this code'

clc;

clear all;

close all;

n=input('Enter n=');

for i=n:-1:2

for j=i-1:-1:1

fprintf('*');

end

fprintf('\n');

end

[Muhammad]

 *
 **
 ***
*****
What changes we do for this type of arrangements