How to implement linear interpolation method in java array? -

i working on simple linear interpolation program. , having troubles when implementing algorithm. assuming there 12 numbers whole, we'll let user input 3 of them(position 0, position 6 , position 12). program calculate other numbers. here piece of code achieve this:

static double[] interpolate(double a, double b){     double[] array = new double[6];     for(int i=0;i<6;i++){         array[i] = + (i-0) * (b-a)/6;     }     return array; }  static double[] interpolate2(double a, double b){     double[] array = new double[13];     for(int i=6;i<=12;i++){         array[i] = + (i-6) * (b-a)/6;     }     return array; } 

as can see, used 2 functions. want find universal function job. however, don't know how find common way represent i-0 , i-6. how fix it? according floating point linear interpolation, know maybe should add formal parameter float f. not quite understand float f mean , how modify code based on it. me? thank you.

if want interpolate intervals different count of numbers, can add count of output numbers function parameter. example:

/***  * interpolating method  * @param start start of interval  * @param end end of interval  * @param count count of output interpolated numbers  * @return array of interpolated number specified count  */ public static double[] interpolate(double start, double end, int count) {     if (count < 2) {         throw new illegalargumentexception("interpolate: illegal count!");     }     double[] array = new double[count + 1];     (int = 0; <= count; ++ i) {         array[i] = start + * (end - start) / count;     }     return array; } 

then can call interpolate(0, 6, 6); or interpolate(6, 12, 6); or interpolate(6, 12, 12); or whatever want.