how to draw epipolar line

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Hello all, I'm getting an error in drawing epipolar line from fundamental matrix. Snap of my code is:

cv::Mat fundamental = cv::findFundamentalMat(
cv::Mat(img_corners), // points in first image
cv::Mat(prevImg_corners), // points in second image
CV_FM_7POINT); // 7-point method

std::vector<cv::Vec3f> lines1;
cv::computeCorrespondEpilines(
img_corners, // image points
1, // in image 1 (can also be 2)
fundamental, // F matrix
lines1); // vector of epipolar lines

// for all epipolar lines

for (vector<cv::Vec3f>::const_iterator it= lines1.begin();
it!= lines1.end(); ++it) {

// draw the line between first and last column

         cv::line(img,
         cv::Point(0,(*it)[2]/(*it)[1]),
         cv::Point(img.cols,((*it)[2] + (*it)[0]*img.cols)/(*it)[1]),
         cv::Scalar(255,255,255));
 }

cv::imshow("Right Image Epilines (FM_7POINT)", img);

And the error is program execution is stop working after first frame. Please suggest what I'm doing wrong. Thanks