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Method: 1. Assign a variable to 0, the syntax is "var sum=0"; 2. Use a for loop with the "<=", " " and " =" operators to achieve accumulation, the syntax is "for(var i=1;i<=100;i ){sum =i;}".
The operating environment of this tutorial: Windows 10 system, JavaScript version 1.8.5, Dell G3 computer.
Accumulation: Add a series of data to a variable. Finally, the cumulative result is obtained.
empty var sum = 0; for(var i = 1;i <= 100;i++){ sum += i; }
empty var h = 100; var sum = 0; for(var i = 0;i < 10;i++){ h = h / 2; sum += h; } sum = sum * 2 + 100;
Accumulation: Multiply a series of data into a variable to get the cumulative result.
empty var n = 100; var result = 1; for(var i = 1;i <= n;i++){ result *= i; }
General form:
Accumulation: v = e;
Accumulation: v *= e;
v represents the cumulative sum/accumulation, and e represents Accumulation/accumulation items
Key points of the algorithm:
(1)Initialization
Initialization v:
Accumulation: v = 0;
Accumulation: v = 1; initialization of
e. If the accumulation/product term is complex, it may be decomposed into several sub-terms and initialized separately. For example, in the problem of calculating pi, the accumulation term is decomposed into three parts: symbol, numerator and denominator. Part
(2) The control condition of the loop
One is a fixed number of times, such as the problem of calculating the bounce distance or the problem of calculating the sum of the first 20 items of the sequence. The number of times is not fixed, but Meet a certain condition: The problem of calculating pi requires that the absolute value of the last term be less than 10-6.
(3) Determine the accumulation/product term
For example, the sum of the first 20 items in a sequence is to use the sum of the current numerator and denominator as the next denominator, and the current denominator as the numerator;
Another example is to find the circumference of pi. The sign is inverted, the denominator is 2, and then the next term is obtained.
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