A method executed by a graph drawing system includes specifying minimum and maximum values of a drawing area in a first axis and a display pixel width along the first axis, determining a step width of a numerical value of the first axis based on a coordinate width along the first axis and the specified display pixel width, the coordinate width being obtained based on the specified minimum and maximum values, changing the minimum or maximum value based on the determined step width and the minimum or maximum value, and determining, based on at least the changed minimum or maximum value, the determined step width and a mathematical expression, coordinates of plot points of the graph, the coordinates including numerical values of variables.