Electronic device having graph display function in which user can set coefficient variation range for fine coefficient value adjustment, and graph display method, and storage medium storing graph display control process program having the same

A method for displaying a graph image by controlling a computer of an electronic device including a display, the method comprising controlling the computer to execute functions comprising:

• displaying a function expression including a coefficient on the display;
• displaying a main graph image which represents the function expression on the display;
• obtaining a second variation range determined by a second minimum value and a second maximum value included in a first variation range determined by a preset first minimum value and a preset first maximum value in accordance with a user operation;
• displaying on the display an operation display element for varying a value of the coefficient;
• varying the value of the coefficient within the second variation range in accordance with a user operation of the operation display element;
• and
• changing the main graph image displayed on the display to a changed main graph image which represents a changed function expression obtained by substituting the value of the coefficient varied in accordance with the user operation of the operation display element into the function expression and displaying the changed main graph image,
• wherein obtaining the second variation range in accordance with the user operation comprises:
• displaying an image indicating a variation range of the main graph image in accordance with the user operation;
• and
• obtaining the second minimum value for displaying a first graph image that is tangent to the image indicating the variation range of the main graph image and the second maximum value for displaying a second graph image that is tangent to the image indicating the variation range of the main graph image, as the second variation range, and
• wherein the method further comprises controlling the computer to execute functions comprising:
• displaying the first graph image that is tangent to the image indicating the variation range of the main graph image and the second graph image that is tangent to the image indicating the variation range of the main graph image.

A non-transitory computer-readable storage medium having stored thereon a program for controlling a computer of an electronic device including a display, the program controlling the computer to execute functions comprising:

• displaying a function expression including a coefficient on the display;
• displaying a main graph image which represents the function expression on the display;
• obtaining a second variation range determined by a second minimum value and a second maximum value included in a first variation range determined by a preset first minimum value and a preset first maximum value in accordance with a user operation;
• displaying on the display an operation display element for varying a value of the coefficient;
• varying the value of the coefficient within the second variation range in accordance with a user operation of the operation display element;
• and
• changing the main graph image displayed on the display to a changed main graph image which represents a changed function expression obtained by substituting the value of the coefficient varied in accordance with the user operation of the operation display element into the function expression and displaying the changed main graph image,
• wherein obtaining the second variation range in accordance with the user operation comprises:
• displaying an image indicating a variation range of the main graph image in accordance with the user operation;
• and
• obtaining the second minimum value for displaying a first graph image that is tangent to the image indicating the variation range of the main graph image and the second maximum value for displaying a second graph image that is tangent to the image indicating the variation range of the main graph image, as the second variation range, and
• wherein the program further controls the computer to execute functions comprising:
• displaying the first graph image that is tangent to the image indicating the variation range of the main graph image and the second graph image that is tangent to the image indicating the variation range of the main graph image.