int fac4(int n,int m){ if(n==m) return n; else{ int mid=(m-n)/2; int x=fac4(n,mid+n); int y=fac4(mid+n+1,m); return x*y; } }
inline mat4 inverse(mat4 const& m) { float coef00 = m[2][2] * m[3][3] - m[3][2] * m[2][3]; float coef02 = m[1][2] * m[3][3] - m[3][2] * m[1][3]; float coef03 = m[1][2] * m[2][3] - m[2][2] * m[1][3]; float coef04 = m[2][1] * m[3][3] - m[3][1] * m[2][3]; float coef06 = m[1][1] * m[3][3] - m[3][1] * m[1][3]; float coef07 = m[1][1] * m[2][3] - m[2][1] * m[1][3]; float coef08 = m[2][1] * m[3][2] - m[3][1] * m[2][2]; float coef10 = m[1][1] * m[3][2] - m[3][1] * m[1][2]; float coef11 = m[1][1] * m[2][2] - m[2][1] * m[1][2]; float coef12 = m[2][0] * m[3][3] - m[3][0] * m[2][3]; float coef14 = m[1][0] * m[3][3] - m[3][0] * m[1][3]; float coef15 = m[1][0] * m[2][3] - m[2][0] * m[1][3]; float coef16 = m[2][0] * m[3][2] - m[3][0] * m[2][2]; float coef18 = m[1][0] * m[3][2] - m[3][0] * m[1][2]; float coef19 = m[1][0] * m[2][2] - m[2][0] * m[1][2]; float coef20 = m[2][0] * m[3][1] - m[3][0] * m[2][1]; float coef22 = m[1][0] * m[3][1] - m[3][0] * m[1][1]; float coef23 = m[1][0] * m[2][1] - m[2][0] * m[1][1]; vec4 fac0(coef00, coef00, coef02, coef03); vec4 fac1(coef04, coef04, coef06, coef07); vec4 fac2(coef08, coef08, coef10, coef11); vec4 fac3(coef12, coef12, coef14, coef15); vec4 fac4(coef16, coef16, coef18, coef19); vec4 fac5(coef20, coef20, coef22, coef23); vec4 v0(m[1][0], m[0][0], m[0][0], m[0][0]); vec4 v1(m[1][1], m[0][1], m[0][1], m[0][1]); vec4 v2(m[1][2], m[0][2], m[0][2], m[0][2]); vec4 v3(m[1][3], m[0][3], m[0][3], m[0][3]); vec4 inv0(v1 * fac0 - v2 * fac1 + v3 * fac2); vec4 inv1(v0 * fac0 - v2 * fac3 + v3 * fac4); vec4 inv2(v0 * fac1 - v1 * fac3 + v3 * fac5); vec4 inv3(v0 * fac2 - v1 * fac4 + v2 * fac5); vec4 signA(+1, -1, +1, -1); vec4 signB(-1, +1, -1, +1); mat4 inv(inv0 * signA, inv1 * signB, inv2 * signA, inv3 * signB); vec4 row0(inv[0][0], inv[1][0], inv[2][0], inv[3][0]); vec4 dot0(m[0] * row0); float dot1 = (dot0.x + dot0.y) + (dot0.z + dot0.w); float one_over_det = 1.f / dot1; return inv * one_over_det; }