lib/ccv_algebra.c

ccv_normalize

double ccv_normalize(ccv_matrix_t* a, ccv_matrix_t** b, int btype, int flag)

Normalize a matrix and return the normalize factor.

• a : the input matrix.
• b : the output matrix.
• btype : the type of output matrix, if 0, ccv will try to match the input matrix for appropriate type.
• flag : CCV_L1 or CCV_L2, for L1 or L2 normalization.

ccv_sat

void ccv_sat(ccv_dense_matrix_t* a, ccv_dense_matrix_t** b, int type, int padding_pattern)

Generate the Summed Area Table.

• a : the input matrix.
• b : the output matrix.
• type : the type of output matrix, if 0, ccv will try to match the input matrix for appropriate type.
• padding_pattern : CCV_NO_PADDING - the first row and the first column in the output matrix is the same as the input matrix. CCV_PADDING_ZERO - the first row and the first column in the output matrix is zero, thus, the output matrix size is 1 larger than the input matrix.

ccv_sum

double ccv_sum(ccv_matrix_t* mat, int flag)

Return the sum of all elements in the matrix.

• mat : the input matrix.
• flag : CCV_UNSIGNED - compute fabs(x) of the elements first and then sum up. CCV_SIGNED - compute the sum normally.

ccv_multiply

void ccv_multiply(ccv_matrix_t* a, ccv_matrix_t* b, ccv_matrix_t** c, int type)

Do element-wise matrix multiplication.

• a : the input matrix.
• b : the input matrix.
• c : the output matrix.
• type : the type of output matrix, if 0, ccv will try to match the input matrix for appropriate type.

ccv_subtract

void ccv_subtract(ccv_matrix_t* a, ccv_matrix_t* b, ccv_matrix_t** c, int type)

Matrix subtraction.

• a : the input matrix.
• b : the input matrix.
• c : the output matrix.
• type : the type of output matrix, if 0, ccv will try to match the input matrix for appropriate type.

ccv_gemm

void ccv_gemm(ccv_matrix_t* a, ccv_matrix_t* b, double alpha, ccv_matrix_t* c, double beta, int transpose, ccv_matrix_t** d, int type)

General purpose matrix multiplication. This function has a hard dependency on cblas library.

As general as it is, it computes:

alpha * A * B + beta * C

whereas A, B, C are matrix, and alpha, beta are scalar.

• a : the input matrix.
• b : the input matrix.
• alpha : the multiplication factor.
• c : the input matrix.
• beta : the multiplication factor.
• transpose : CCV_A_TRANSPOSE, CCV_B_TRANSPOSE to indicate if matrix A or B need to be transposed first before multiplication.
• d : the output matrix.
• type : the type of output matrix, if 0, ccv will try to match the input matrix for appropriate type.

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