need to generate sine wave using C

[saya407]

I am working on a project to code a program that generates sum of two sine waves of different freq,and has a sampling freq of 100khz(1 lac samples).
The following is what i could find out about generating sine wave,but don't know what values the variables should hold.

C is very new for me,please help me.

Enter the initial step-size in degrees
 Enter the number of lines to be displayed in the graph
    
   current_step_size = initial_step_size
      
     for (line_count = 0; line_count < no_of_lines; line_count++)
     {
      result = sin(current_step_size);
      for (sine_count = -1; sine_count <= 1; sine_count += 0.01)
      {
       if (result == sine_count)
            }
   Increment step size 
      current_step_size += initial_step_size;         
     }
     
     return 0;

[ssharish2005]

Well its more than that code you need to draw sin wave. If you want to display the numerical data in the form on graph you will have to start looking into graphical programming library such as the openGL.

But from the code there are two variables which needs to be inputted, one of the step size. This depends on the application your program is designed. For example: assuming your drawing a sine wave of all even angle between 0 - 90. Your step size would be 2 starting from 0. And the other variable which you would need to initialise would be number of lines, which is in a complete contrast to the how big the graph you will like it to be.

ssharish

[quzah]

How do you plot a sign wave on a piece of graph paper? Write out the steps to do that, and you'll understand how to do it here.


Quzah.

[saya407]

displaying the graph isn't important,mere generation will do. Since i am from electronics field, does the no. of lines means amplitude and step size means time period of the signal? and where shall i put the sampling frequency? I am struggling with coding, please help me. I ll be gratefull. thank you.

[Salem]

Why don't you rename the variables to be say "deltaTime" and "amplitude".

As in say
amplitude = sin(deltaTime)

[saya407]

Please can i get at least a rough idea of a code which would help me understand what i am supposed to do.

[quzah]

I'd suggest some reading: Sine wave - Wikipedia, the free encyclopedia

Like I said earlier, can you work out how to do one on paper? If not, you can't do this.


Quzah.

[saya407]

ok thank you. the wikipedia and the following page : Creating a Sine Wave gave me some idea to workout. will post my progress soon. thanks every1 for your valuable guidance

[saya407]

i got up with this following code now. Could someone help me with displaying the output of this program because the last printf statement isnt getting displayed in the output screen.

#include<stdio.h>
#include<conio.h>
#include<math.h>
#define pi 3.414
void main()
{
 int freq,fs,amplitude,cycle;
 double angle,increment,sample;
 printf("enter the desired frequency of the signal:\n");
 scanf("%d",&freq);
 printf("enter the desired sampling frequency:\n");
 scanf("%d",&fs);
 printf("enter the amplitude of the signal:\n");
 scanf("%d",&amplitude);
 angle=0;
 increment=(2*pi)/(fs/freq);
    for (cycle=1;cycle<=freq;cycle++)
    {
        while (angle<=(2*pi))
        {
            sample=amplitude * sin(angle);
            angle=angle+increment;
        }
        printf("%lf/t",&sample);/*here the output is not getting displayed*/
    }
 }

[Salem]

Get a better compiler, one which can tell you when you mess up printf/scanf calls (by spraying random & all over the place for example)

Eg.
$ gcc -Wall -Wextra foo.c -lm
foo.c:4: warning: return type of ‘main’ is not ‘int’
foo.c: In function ‘main’:
foo.c:20: warning: implicit declaration of function ‘sin’
foo.c:20: warning: incompatible implicit declaration of built-in function ‘sin’
foo.c:23: warning: format ‘%lf’ expects type ‘double’, but argument 2 has type ‘double *’

[GReaper]

Also, PI truncated to three decimal digits is "3.141", rounded to nearest is "3.142"

Here it is.

[saya407]

what am i suppposed to do to rectify these

foo.c:20: warning: implicit declaration of function ‘sin’
foo.c:20: warning: incompatible implicit declaration of built-in function ‘sin’
foo.c:23: warning: format ‘%lf’ expects type ‘double’, but argument 2 has type ‘double *’

[GReaper]

#include <math.h>

remove the "&" from printf.

[saya407]

ok as suggested, i removed the '&' included math.h, program is running but its going into infinite loop and terminating abruptly. i am presently using an ide called "dev c++"... please guide me to proceed..

[Salem]

You need to post your latest code.