Shell Programming and Scripting

$ cat file
10    464310.16
20    464309.44
30    464309.02
40    464316.93

$ cat int.sh
#!/bin/bash

awk '
    {
     x[FNR]=$1
     y[FNR]=$2
    }
  
END{
      for(i=1;i<=NR;i++){
                                a=0
                                x1=x[i];x3=x[i+1]
                                y1=y[i];y3=y[i+1]
      for(j=1;j<=x3-x1+1;j++){
                              if((x2=x1+a) <= x3 ){
                                                    print x2,sprintf("%.2f",y1+(x2-x1)*(y3-y1)/(x3-x1))
                                                    a++
                                                  }
                             }
                        } 
                       
    }' file

$ bash int.sh

10 464310.16
11 464310.09
12 464310.02
13 464309.94
14 464309.87
15 464309.80
16 464309.73
17 464309.66
18 464309.58
19 464309.51
20 464309.44
21 464309.40
22 464309.36
23 464309.31
24 464309.27
25 464309.23
26 464309.19
27 464309.15
28 464309.10
29 464309.06
30 464309.02
31 464309.81
32 464310.60
33 464311.39
34 464312.18
35 464312.97
36 464313.77
37 464314.56
38 464315.35
39 464316.14
40 464316.93

awk     '               {X[NR]=$1; Y[NR]=$2}
         NR==1          {next}
                        {a=(Y[NR]-Y[NR-1])/(X[NR]-X[NR-1])              # calculate linear slope
                         Y0=Y[NR-1]-a*X[NR-1]                           # calc. Y axis intercept
                         for (x=X[NR-1]; x<X[NR]; x++)                  # step through abscissa values 
                                {y=Y0+a*x; printf "%d\t%8.2f\n", x,y}   # calc. function value; print
                        }
         END            {printf "%d\t%8.2f\n", $1, $2}                  # print final X,Y point

awk     '               {XL=X; YL=Y; X=$1; Y=$2}
         NR==1          {next}
                        {a=(Y-YL)/(X-XL)                                # calculate linear slope
                         Y0=YL-a*XL                                     # calc. Y axis intercept
                         for (x=XL; x<X; x++)                           # step through abscissa values
                                {y=Y0+a*x; printf "%d\t%8.2f\n", x,y}   # calc. function value; print
                        }
         END            {printf "%d\t%8.2f\n", $1, $2}                  # print final X,Y point
        ' file

#!/bin/bash

awk '
    {
     x[FNR]=$1
     y[FNR]=$2
    }
  
END{
      for(i=1;i<=NR;i++){
                                a=0
                                x1=x[i];x3=x[i+1]
                                y1=y[i];y3=y[i+1]
      for(j=1;j<=x3-x1+1;j++){
                              if((x2=x1+a) <= x3 ){
                                                    print x2,sprintf("%.2f",y1+(x2-x1)*(y3-y1)/(x3-x1))
                                                    a++
                                                  }
                             }
                        } 
                       
    }' file | uniq > output