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gdchart0.11.4dev/gdchart.c  view on Meta::CPAN

			v1 = vals[j];
			p1 = j;
			}
	if( p1==-1 || p2==-1 ||							/* need both */
		p1 == p2 )									/* idiot */
		{
		vals[interp_point] = GDC_NOVALUE;
		return;
		}

	/* Point-slope formula */
	vals[interp_point] = ((v2-v1)/(float)(p2-p1)) * (float)(interp_point-p1) + v1;
	return;
}

/* ========================================================================= */
/* little error checking  0: ok,                      */
/*                     -ret: error no graph output    */
/*                      ret: error graph out          */
/* watch out for # params and array sizes==num_points */
/* ------------------------------------------------------------------------- */