Provided by: libssl-doc_1.0.2g-1ubuntu4.20_all 

NAME
BN_mod_inverse - compute inverse modulo n
SYNOPSIS
#include <openssl/bn.h>
BIGNUM *BN_mod_inverse(BIGNUM *r, BIGNUM *a, const BIGNUM *n,
BN_CTX *ctx);
DESCRIPTION
BN_mod_inverse() computes the inverse of a modulo n places the result in r ("(a*r)%n==1"). If r is NULL,
a new BIGNUM is created.
ctx is a previously allocated BN_CTX used for temporary variables. r may be the same BIGNUM as a or n.
RETURN VALUES
BN_mod_inverse() returns the BIGNUM containing the inverse, and NULL on error. The error codes can be
obtained by ERR_get_error(3).
SEE ALSO
bn(3), ERR_get_error(3), BN_add(3)
HISTORY
BN_mod_inverse() is available in all versions of SSLeay and OpenSSL.
1.0.2g 2016-03-01 BN_mod_inverse(3SSL)