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  1. #include<stdio.h>
  2. #include<math.h>
  3. void
  4. show(float a[100][100],int n,int m)
  5. {
  6. 	int i,j;
  7. 	for(i=0;i<n;i++)
  8. 	{
  9. 		for(j=0;j<m;j++)
  10. 		{
  11. 				printf("%f ",a[i][j]);
  12. 			}
  13. 				printf("\n");
  14. 		}
  15.  
  16. 	}
  17. int
  18. main()
  19. {
  20. 	float a[100][100];
  21. 	float t,a1[100],sum=0;
  22. 	int p,r,c,n,m,k;
  23. 	int bool=1;
  24. 	float x;
  25. 	int i,j;
  26. 	scanf("%d%d",&n,&m);
  27. 	for(i=0;i<n;i++)
  28. 	{
  29. 		for(j=0;j<m;j++)
  30. 		{
  31. 				scanf("%f",&a[i][j]);
  32. 		}
  33. 	}
  34. 	p=0;
  35. 	for(i=0;i<n;i++)
  36. 	{
  37. 			bool=1;
  38. 				for(j=0;j<m;j++)
  39. 				{
  40. 					if(a[i][j]!=0)
  41. 					{
  42. 						bool=0;
  43. 						break;
  44. 					}
  45. 				}
  46.  
  47.  
  48. 				if(bool==1)
  49. 				{
  50. 							for(k=0;k<m;k++)
  51. 							{
  52.  
  53. 								t=a[n][k];
  54. 								a[n][k]=a[i][k];
  55. 								a[i][k]=t;
  56. 							}
  57.  
  58. 					n--;
  59. 					}
  60.  
  61. 		}
  62.  
  63. 	while(p<n&&p<m)
  64. 	{
  65. 		jump:
  66. 		r=1;
  67. 		while(a[p][p]==0)
  68. 		{
  69. 			if(p+r>n-1)
  70. 			{
  71. 				p=p+1;
  72. 				goto jump;
  73. 				}
  74. 						for(c=0;c<m;c++)
  75. 						{
  76. 						t=a[p+r][c];
  77. 						a[p+r][c]=a[r][c];
  78. 						a[r][c]=t;
  79. 						}
  80. 				r=r+1;
  81. 		}
  82. 		for(r=1;r<n-p;r++)
  83. 		{
  84.  
  85. 				x=(a[p+r][p])/a[p][p];
  86. 				if(a[p+r][p]!=0)
  87. 				{
  88. 					for(c=0;c<m;c++)
  89. 					{
  90. 						a[p+r][c]=(a[p][c]*x)-a[p+r][c];
  91. 					}
  92. 				}
  93. 		}
  94. 		p++;
  95.     printf("\n");
  96. 	}
  97. 	show(a,n,m);
  98.  
  99. 	for(i=0;i<100;i++)
  100. 	{
  101. 			a1[i]=(float)1;
  102. 		}
  103. 		for(i=n-1;i>=0;i--)
  104. 		{
  105. 				sum=0;
  106. 				for(j=m-2;j>i;j--)
  107. 				{
  108. 					sum+=a1[j]*a[i][j];
  109. 					}
  110.  
  111. 					if(i<n-1)
  112. 					{
  113. 			a[i][m-1]=a[i][m-1]-sum;
  114. 						}
  115. 						if(i==n-1)
  116. 						{
  117.                             sum+=a1[j]*a[i][j];
  118. 							}
  119. 						a1[i]=a[i][m-1]/a[i][j];
  120. 			}
  121. 			for(i=0;i<=n-1;i++)
  122. 			printf("\n%dst variable is %f \n",i+1,a1[i]);
  123. 			getchar();
  124. 	return 0;
  125. }
  126.  
stdin
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3
4
3 4 1 6
2 -1 2 -5
1 3 -1 9
compilation info 
prog.c: In function ‘main’:
prog.c:26: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result
prog.c:31: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result
stdout
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3.000000 4.000000 1.000000 6.000000 
0.000000 3.666667 -1.333333 9.000000 
-0.000000 0.000000 -0.727273 2.909091 

1st variable is 2.000000 

2st variable is 1.000000 

3st variable is -4.000000
https://ideone.com/v2m8Z
language:
C (gcc 8.3)
created:
12 years ago
visibility:
public

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