How to find the number of elements greater than a certain number and the total number of elements in the matrix in MATLAB If matrix A = [1 2 3 5; 3 5 3 2], then the number of elements greater than 3 and the total number of elements in the matrix

How to find the number of elements greater than a certain number and the total number of elements in the matrix in MATLAB If matrix A = [1 2 3 5; 3 5 3 2], then the number of elements greater than 3 and the total number of elements in the matrix

A=[1 2 3 5 ; 3 5 3 2]
sum(sum(A>3))
[a,b]=size(A);
a*b

How to find the position of a number in the matrix in MATLAB?

>> x=magic(4)
x =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1
>> [i,j]=find(x==7)
i =
three
j =
two

Expand the side of a cylinder to get a square with side length of 6.28 decimeters. The volume of the cylinder is () cubic decimeters
A. 2B. 2πC. 19.7192

2 × 6.28, = 3.14 × 1 × 6.28, = 19.7192 (cubic decimeter), answer: the volume of the cylinder is 19.7192 cubic decimeter; so choose: C

What is the relationship between the shape of the light spot and the shape of the light transmission hole of the leaf

No contact
The light spot on the ground is round, which has nothing to do with the gap between the leaves
The real image of the sun is on the ground, so it is round

Note that the meaning of pedestrian signs is
A is used to remind the driver to slow down
B is used to remind drivers to slow down and pay attention to pedestrians ahead
C remind drivers to avoid pedestrians

C

If the circumference of a rectangle is 20cm and the length is xcm, then the area of the rectangle is ()
A. x（10-x）cm2B. x（20-x）cm2C. 12(20−x)cm2D. x（20-2x）cm2

If the width is: 20 − 2x2 = 10-x, then the area is: X (10-x)

Calculation: 5 times 8:1 + 8 times 11:1 + 11 times 14:1 +. + 98 times 101:1?

5 by 1 / 8 + 8 by 1 / 11 + 11 by 1 / 14 +. + 98 by 1 / 101
=（1/5-1/8+1/8-1/11+1/11-1/14+…… +1/98-1/101）÷3
=（1/5-1/101）÷3
=96/505÷3
=32/505

Given that f (x) = a + 1 / 2 ^ X-1 is an odd function, the value of constant a and the range of F (x) are obtained

F (x) is an odd function, f (- x) = - f (x)
f(x)+f(-x)=0
There is
a+1/(2^x-1)+a+1/[2^(-x)-1]
=2a+1/(2^x-1)+1/[2^(-x)-1]
=2a+1/(2^x-1)+ 2^x/(1-2^x)
=2a+(1-2^x)/(2^x-1)
=2a-1
=0
So a = 1 / 2
f(x)=1/2+1/(2^x-1)
2^x>0
2^x-1>-1
1/(2^x-1)∈(-∞,-1)∪(0,+∞)
Range: (- ∞, - 1 / 2) ∪ (1 / 2, + ∞)

The figure below is composed of a square and two rectangles. Find the perimeter of the figure?
 

This question is a little similar to the three views of three-dimensional graphics
Let's see
So perimeter = 50 × 2 + (20 + 9 + 15) × 2 = 100 + 88 = 188

Use 3, 8, - 3, - 8 to calculate 24 o'clock

8/[3-（-8）/（-3）]