bicubic_coef.c
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bicubic_coef.c
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			void bicubic_coef(double y, double y1, double y2, double y12, double d1, double d2, double **c)
			{
			const int wt[16][16] =
			{{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
			{0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0},
			{ -3, 0, 0, 3, 0, 0, 0, 0, -2, 0, 0, -1, 0, 0, 0, 0},
			{2, 0, 0, -2, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0},
			{0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
			{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0},
			{0, 0, 0, 0, -3, 0, 0, 3, 0, 0, 0, 0, -2, 0, 0, -1},
			{0, 0, 0, 0, 2, 0, 0, -2, 0, 0, 0, 0, 1, 0, 0, 1},
			{ -3, 3, 0, 0, -2, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
			{0, 0, 0, 0, 0, 0, 0, 0, -3, 3, 0, 0, -2, -1, 0, 0},
			{9, -9, 9, -9, 6, 3, -3, -6, 6, -6, -3, 3, 4, 2, 1, 2},
			{ -6, 6, -6, 6, -4, -2, 2, 4, -3, 3, 3, -3, -2, -1, -1, -2},
			{2, -2, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
			{0, 0, 0, 0, 0, 0, 0, 0, 2, -2, 0, 0, 1, 1, 0, 0},
			{ -6, 6, -6, 6, -3, -3, 3, 3, -4, 4, 2, -2, -2, -2, -1, -1},
			{4, -4, 4, -4, 2, 2, -2, -2, 2, -2, -2, 2, 1, 1, 1, 1}
			};
			int l, k, j, i;
			double xx, d1d2, cl[16], x[16];

			d1d2 = d1 * d2;
			for (i = 0; i < 4; i++)
			{
			x[i] = y[i];
			x[i+4] = y1[i] * d1;
			x[i+8] = y2[i] * d2;
			x[i+12] = y12[i] * d1d2;
			}
			for (i = 0; i < 16; i++)
			{
			xx = 0.0;
			for (k = 0; k <= 15; k++) xx += wt[i][k] * x[k];
			cl[i] = xx;
			}
			l = 0;
			for (i = 0; i < 4; i++)
			for (j = 0; j < 4; j++) c[i][j] = cl[l++];
			}