How does matlab draw the curve of known formula and how does excel draw the function curve image?

Friends must encounter the problem of drawing function curves ！ If you want to draw a function curve quickly and accurately , Can use EXCEL The chart function of , It can make your curves both standard and beautiful . You can also put multiple function images into the same chart for comparison . As shown in the figure below, it is in Excel Positive drawn in 、 Cosine function image ：

One 、 Prepare the data

1、 First, according to the function expression Prepare a set of data , Then use the data to draw the function image in the chart . In this example, the data is placed in the area A:C In the column , among A The value in the column is the value of the function argument , stay A Column A1 Cell input "X=", Indicates that this is an independent variable ,A2、A3 And the following cells, input each value of the independent variable from small to large , When actually entering , The input method of equal difference sequence is usually used . How to determine the initial value of the independent variable , Value range , What is the step size between data points , This is to judge according to the specific characteristics of the function . If you want to quickly find the extreme value of the function or see its development trend , The given data points do not have to be equal difference , Can be given as needed . Pictured , The value range I use for drawing is [-6,6], The interval between values is “0.1”.

2、B Column sum C List the values of the two function variables . stay B Column B1 General written expression of cell input function ,y=sin(x), You can add some descriptive characters ; stay B2 Enter the formula according to the function expression in the cell “=SIN(A2)” Then select B2 Cell , Fill drop-down . Also in C Column input function expression and formula . Pictured , So the data is ready .

Two 、 Draw function image

1、 Select... In the ribbon “ Insert ” tab , stay “ Chart ” Click... In the group “ Scatter plot → Scatter with smooth lines ”.

2、Excel Insert into the chart area as shown in the figure below , And add the function of chart tool in the function area “ Design ”、“ Layout ”“ Format ” tab .

3、 First, select the data of the chart , Right click in the chart area , Choose... From the shortcut menu that pops up “ Select data ”.

4、 In the pop-up “ Select data source ” Select... In the dialog box “ add to ”, eject “ Edit data series ” Dialog box , Pictured , Choose the data we have prepared , spot “ determine ”. So the sine function image is added , Also add the cosine function .

5、 After adding the data function, the image will come out , Pictured , We found that there were many places that didn't meet the requirements , What needs to be revised .

6、 First, the legend and grid lines , We don't need to , You can delete . Select the legend in the chart , Press Delete Key delete , Then select the grid line , Press Delete Key delete .

7、 Secondly, the scale of the two coordinate axes does not meet the requirements , In order to better adjust the coordinate axis , First, set the chart area to square , stay “ Format ” tab “ size ” In the group , Adjust the height and width to the same .

8、 Right click on each coordinate axis , Choose... From the shortcut menu that pops up “ Format axis ”.

9、 In the pop-up “ Format axis ” In the dialog box “ Axis options ” In the column , take “ minimum value ”、“ Maximum ”、“ Main scale unit ” Is set to “ Fix ”, And enter... In the following text boxes “-6”、“6”、“1”, single click “ close ” Button . The two axes are set in the same way .

10、 then , After setting the line color and linetype of the function image , Right click the function image , Choose... From the shortcut menu that pops up “ Format data series ”.

11、 In the pop-up “ Format data series ” In the dialog box “ line color ”、“ Linetype ” In the column , Set the line color and linetype of the function image respectively .

12、 Finally, add a function expression to each image , First click to select a function image , Then click on a data point to select a data point , Right click on the data point , Choose... From the shortcut menu that pops up “ Add data label ”.

13、 Then right click on the data point , Choose... From the shortcut menu that pops up “ Format data labels ”.

14、 In the pop-up “ Format data labels ” In the dialog box , Set the contents of the function label respectively 、 Position and border color, etc .

15、 At this point, the standard and beautiful function image is set up . The following is my parabola function image .