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66 lines
2.0 KiB
C++
66 lines
2.0 KiB
C++
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/*-------------- BACKWARD DIFFERENCES GENERATION FOR INTERPOLATION ----*/
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/* THE PROGRAM GENERATES A BACKWARD DIFFERENCES TABLE FROM GIVEN
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DATA. THE VALUES OF x AND CORRESPONDING y = f(x) ARE TO BE
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ENTERED IN THE ARRAY FORMAT.
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INPUTS : 1) Number of entries of the data.
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2) Values of 'x' & corresponding y = f(x).
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OUTPUTS : Backward difference table array. */
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/*------------------------------ PROGRAM --------------------------*/
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#include<stdio.h>
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#include<math.h>
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#include<stdlib.h>
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#include<conio.h>
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void main()
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{
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double y[20][20],x[20];
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/* ARRAY OF N*N ELEMENTS FOR BACKWARD DIFFERENCE TABLE */
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int i,j,k,n;
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clrscr();
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printf("\n\tBACKWARD DIFFERENCES GENERATION FOR INTERPOLATION");
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printf("\n\n The form of equation is y = f(x)\n");
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printf("\n\nEnter the number of entries (max 20) = ");
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scanf("%d",&n); /* ENTER NUMBER OF ENTRIES IN THE TABLE */
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for(i = 0; i < n; i++)
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{
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/* LOOP TO GET x AND y = f(x) IN THE TABLE */
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printf("x%d = ",i);
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scanf("%lf",&x[i]);
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printf(" y%d = ",i);
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scanf("%lf",&y[i][0]);
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}
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k = 0;
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for(j = 1; j < n; j++)
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{
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/* LOOP TO CALCULATE BACKWARD DIFFERENCES */
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k++;
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for(i = n-1; i >= k; i--)
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{
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y[i][j] = y[i][j-1] - y[i-1][j-1];
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}
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}
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k = n ;
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clrscr();
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printf("\n The backward difference table is as follows . . .\n");
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printf("\n\tx\ty\tDy\tD2y\tD3y\tD4y\tD5y\tD6y\n");
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for(i = 0; i < n; i++)
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{
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/* LOOP TO PRINT BACKWARD DIFFERENCES */
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printf("\nx%d = %4.2lf",i,x[i]);
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for(j = 0; j < i+1; j++)
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{
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printf("\t%4.2lf ",y[i][j]);
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}
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printf("\n");
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}
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}
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/*------------------------------End of program-------------------------*/ |