Quadratic and Gaussian Blur

This is a paint like program, where on a click or drag, a circle with certain fills will appear.

I'm having issues with the Quadratic and Gaussian Brushes. Each provide me with a small dot, the QuadraticBush is about 20 pixels in diameter and the GaussianBrush is 1 pixel. Each start with a radius and flow of 128. These are the two functions that create the mask which stores the flow.

They are wrapped in a double for loop holding i as each row and j as each column.

Size is the width and height of the array.
Distance is the distance from the click location to each pixel in the mask.
Flow can be from 0 to 255 and represents the amount of color applied.
Rho is some constant for the Gaussian equation.

Quadratic:

Code:

---

if( distance <= (double)radius )  {
        if (distance < 1) {
                m_mask[i*(size-1)+j] = m_flow;
        } else {
                m_mask[i*(size-1)+j] = m_flow / (distance * distance);
                if (m_mask[i*(size-1)+j] > m_flow) {
                        m_mask[i*(size-1)+j] = m_flow;
                }
        }
} else {
        m_mask[i*(size-1)+j] = 0;
}

---

Gaussian:

Code:

---

if( distance <= (double)radius )  {
        float base = 1 /(2 * PI * rho * rho);
        float exponent = -1.0 * ((distance * distance) / (2.0 * rho * rho));
        m_mask[i*(size-1)+j] = m_flow * base * exp(exponent);
        if (m_mask[i*(size-1)+j] > m_flow) {
                m_mask[i*(size-1)+j] = m_flow;
        }
} else {
        m_mask[i*(size-1)+j] = 0;
}

---

This is a linear blur which works just fine. It goes from 100% inside and 0% outside.

Linear:

Code:

---

        int radius = m_radius;
        int size = radius*2 +1;
        int count=0;
        int arraysize = size * size;
        m_mask = new float[arraysize];
        double distance;
        for(int i=0; i<size; i++) {
                for(int j=0; j<size; j++) {
                        distance = sqrt((double)((radius-i)*(radius-i) + (radius-j)*(radius-j)));
                        if( distance <= (double)radius )  {
                                m_mask[i*(size-1)+j] = ((radius-distance)/(double)radius) * m_flow;
                        } else {
                                m_mask[i*(size-1)+j] = 0;
                        }
                }
        }

---

Any help would be great.