18 basisGradient[13] = 0.5 * (1.0 - rr) * (1.0 + rr) * (-1.0 + 2.0 * ss);
19 basisGradient[14] = 0.0;
21 basisGradient[15] = 0.5 * (1.0 - ss) * (1.0 + ss) * (1.0 + 2.0 * rr);
22 basisGradient[16] = -rr * (1.0 + rr) * ss;
23 basisGradient[17] = 0.0;
25 basisGradient[18] = -ss * (1.0 + ss) * rr;
26 basisGradient[19] = 0.5 * (1.0 - rr) * (1.0 + rr) * (1.0 + 2.0 * ss);
27 basisGradient[20] = 0.0;
29 basisGradient[21] = 0.5 * (1.0 - ss) * (1.0 + ss) * (-1.0 + 2.0 * rr);
30 basisGradient[22] = (1.0 - rr) * rr * ss;
31 basisGradient[23] = 0.0;
33 basisGradient[24] = -2.0 * (1.0 - ss) * (1.0 + ss) * rr;
34 basisGradient[25] = -2.0 * (1.0 - rr) * (1.0 + rr) * ss;
35 basisGradient[26] = 0.0;