Thread: Dave or someone please help

  1. #1
    Registered User
    Join Date
    Oct 2003
    Posts
    38

    Dave or someone please help

    Originally posted by Dave_Sinkula

    Code:
    --------------------------------------------------------------------------------/* calculation description
    Y[0] = x(0) * x(0) + x(1) * x(1) + x(2) * x(2) + x(3) * x(3)
    Y[1] = x(0) * x(1) + x(1) * x(2) + x(2) * x(3)
    Y[2] = x(0) * x(2) + x(1) * x(3)
    Y[3] = x(0) * x(3)
    */
    #include <stdio.h>
    
    #define ARRAYSIZE(x) (sizeof(x)/sizeof(*(x)))
    
    int main(void)
    {
       int x[] = {1,2,3,4}, y [ ARRAYSIZE(x) ];
       size_t i,j;
       for(j = 0; j < ARRAYSIZE(y); ++j)
       {
          y[j] = 0;
          printf("y[%d] =", (int)j);
          for(i = j; i < ARRAYSIZE(x); ++i)
          {
             printf("%s x[%d] * x[%d]", i != j ? " +" : "", (int)(i - j), (int)i);
             y[j] += x[i - j] * x[i];
          }
          printf(" = %d\n", y[j]);
       }
       return 0;
    }
    
    /* my output
    y[0] = x[0] * x[0] + x[1] * x[1] + x[2] * x[2] + x[3] * x[3] = 30
    y[1] = x[0] * x[1] + x[1] * x[2] + x[2] * x[3] = 20
    y[2] = x[0] * x[2] + x[1] * x[3] = 11
    y[3] = x[0] * x[3] = 4
    */--------------------------------------------------------------------------------
    Dave,
    How about if x[] is not as {1,2,3,4},but is the numerical data stored in a file line by line? how to perform such shifting?

  2. #2
    ATH0 quzah's Avatar
    Join Date
    Oct 2001
    Posts
    14,826
    Simple, read a line into an array, and then perform whatever you need to on it. Read the next line, and so on.

    Quzah.
    Hope is the first step on the road to disappointment.

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