i need icons for my chart builder for line functions, 18x18p with 1px padding, focus on main characteristic of each line function. it should be clearly visible (1.5 - 2px stroke width).used in a segmented select where those function icons stand side by side and one should intuitively understand how those differ 'line_function_basis', 'line_function_linear', 'line_function_monotone_x', 'line_function_monotone_y', 'line_function_natural', 'line_function_step', 'line_function_step_after', 'line_function_step_before', 'line_function_step_categorial',

The image shows a black and white poster with a set of symbols and text written on it. The symbols are arranged in a grid pattern and the text is written in a bold font. The background of the poster is a light grey color.