using arrays for calculations

[johnnyjohn20]

MY QUESTION IS BASED ON A COURSEWORK

I am trying to produce a sin wave using *'s to represent sample values for 1 cycle of the wave. For example when the user enters 7 the output should look like this:

.........................................................*
..........................................................................* 
..........................................................................*
.........................................................*
.......................................*
.......................................*
.........................................................*

please ignore the "......" its the only way i can get the *'s to stay where they are
My attempts

To try and get a load of values that can be 'plotted' as *'s, i have used a counter to count 0 upto the value the user has entered. leaving me with for this example 1 -> 7 (values to help me split up the sine wave) These values are placed into an array a[x]. Next i have said a[10]=360/a[x] producing equal degree values, 60, 120, 180, 240, 300, 360. Then i have to either convert them to radians before take the sin of them or leave them in degrees(but as this is courswork i need to figure that bit out!)

int a[30];           //array called a which has 100 integers
int b[10000];
int x;



for ( x=1; x<=rate-1; x++ ) {  //does counting x=1 -> x=rate-1
    a[x] = x;                    

    b[0] = (360 / a[x]);

    cout << b[0] << endl;}

note counter starts at one to avoid 360 / 0*

At the moment my program works in terms of prompting the user to enter a value such as 7 and then working out the degrees for 1 cycle (360).

My problem lies with taking the sin of the values within b[0] which forever produces an overload error. Is there an easier way of showing the degree values for one cycle. I have literally gone through every possibilie i can think off. For example:

if ( rate = 7 ) {
    int a [7] = { 0, 90, 120, 180, 240, 300, 360 } }

 ***** AND ALSO ******

for ( x=1; x<=rate-1; x++ ){
         a[1] = x;
        a[2] = 360 / x;
         cout << a[2] <<  endl;}
         a[3] = sin(a[2]);
         b[a2] = a[2]; }

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

For all the coding above i am trying to acheive the sine of each of the degree angles so i can put them in the formula below:

* output position = centrepoint + scalefactor * sin(radian angle)

Can anyone provide me with any tips on how they would calculate and store the degree values so i can use a sin function on them. Something easier than how im going about doing it?

I know this post is confusing but i will explain it again if need be.

Thank you for your time!

[Jishnu]

>a[10]=360/a[x]

Didn't understand why.

>int a[[B][U]30[/U][/B]]; //array called a which has 100 integers

How 100?

[Jishnu]

You are approaching the problem in a very roundabout manner. Try something like this.

double no,a[10]; // Try using dynamic memory allocation here.
int i;
// Let the user input value of no here.
no=360/no; // equal spacing between each array element.
for(i=1;i<=no;i++)
{
	a[i]=sin(PI*i*no/180);
}
// Display a[i] here.

[johnnyjohn20]

The 100 integer came from a previous attempt where i had set a[100] and commented //a has 100 integers. Later i decided to edit the number of elements but didnt adjust the comment beside.

John

[Jishnu]

By the way, you should have posted this in the C forum. There is nothing specific to C++ in this thread.

[Rashakil Fol]

By the way, you should have posted this in the C forum. There is nothing specific to C++ in this thread.

No, the C++ forum is appropriate; he is using C++, not C. If he posted in the C forum people would be wondering why 'cout' is in his code.

[Jishnu]

right. but he does not need to use cout in order to manipulate pointers. though, what you said is very much right.

[iamthwee]

right. but he does not need to use cout in order to manipulate pointers. though, what you said is very much right.

Erm, I think he is using * to represent asterisks not pointers. The '*' is an arbitary character used for displaying the sin wave...

[Jishnu]

I should have written

right. but he does not need to use cout in order to manipulate arrays. though, what you said is very much right.

then. Okay?