Specifies the width and height of the display in blocks. (The display is always square, so the same number is used for both.) The size of the blocks in pixels is specified by the block size field, below.

For example, if you set this field to 10, and set the block size to 5, then the display will be 10×10 blocks square, or 50×50 pixels square.

Specifies the width and height in pixels of each block. (Blocks are always square, so the same number is used for both.) The number of blocks in each direction is specified by the width in blocks field, above.

For example, if you set this field to 5, and set width in blocks to 10, then the display will be 50×50 pixels square, or 10×10 blocks square.

Specifies the number at the center of the spiral. In Ulam's original version, which is the default here, the starting number was 1, but you can choose any integer, including negative numbers.

Specifies the background color of the display.

This checkbox toggles the display of prime blocks on and off.

This field specifies the shape plotted in prime blocks.

Specifies the diameter of the prime shapes in pixels.

Specifies the color of the prime shapes.

This field specifies the opacity of the prime shapes in the range 0.0 to 1.0, where 0.0 is completely transparent, and 1.0 is completely opaque.

If checked, this toggles on the display of prime connectors, lines running between neighboring prime blocks.

Determines the maximum number of steps there can be between two primes for a connector to be drawn.

Specifies the color of the prime connectors.

This field specifies the opacity of the prime connectors in the range 0.0 to 1.0, where 0.0 is completely transparent, and 1.0 is completely opaque.

Determines the angles at which connectors between primes can be drawn. By default, 90%deg; and 45° connectors are drawn. Checking "others" will connect primes at any angle as long as they are within the neighborhood specified by the steps field.

This checkbox determines whether blocks containing composite numbers will be plotted.

This field specifies the shape plotted in composite blocks.

If scaled ranges is checked, the composite size, color, and opacity fields will have minimum and maximum values, and the actual value chosen will be interpolated between the two based on the number of prime factors each composite number has.

Specifies the diameter of the composite shapes in pixels. If scaled ranges are in use, a minimum and maximum size can be specified.

Specifies the color of the composite shapes. If scaled ranges are in use, a minimum and maximum color can be specified.

This field specifies the opacity of the composite shapes in the range 0.0 to 1.0, where 0.0 is completely transparent, and 1.0 is completely opaque. If scaled ranges are in use, a minimum and maximum opacity can be specified.

These fields specify the initial length in blocks of the horizontal and vertical sides of the spiral. In the original Ulam spiral, this value was 1.

This is a comma-delimited list of zero or more positive integers greater than one whose multiples will be excluded from the spiral. For example, supplying 2 will eliminate all even numbers.

If selected, this option applies the 1/n of base opacity to connectors of n units. In less mathematical terms, the longer the connector, the less opaque it is.

This field determines the type of spiral in which the numbers are arranged. The default is the original Ulam spiral. The rest have been newly devised for this program.

Determines the width of the prime block outline. Setting this to zero disables the outline.

This field determines the shape of corners where lines join in a prime block. This has no effect on the disk shape, which has no corners, but will affect other shapes. It also has no effect if outlines are disabled by setting their width to zero.

This determines the offset of the shadow of the prime blocks relative to the block position. Up and to the left are negative and down and to the right are positive.

Sets the size of the shadow blur in pixels.