Illustration of preallocating a vector, MATLAB in Engineering

Illustration of Preallocating a Vector:

Illustration of calling the function:

>> myveccumsum([5 9 4])

ans =

    5  14  18

At the first time in the loop, outvec will be [5]. Then in the second time, runsum will be 14 and outvec will store [5 14]. Lastly, runsum will be 18 and outvec will store [5 14 18].

Though this technique works, it is ineffective. The other method includes referring to each index in the output vector, and placing every partial sum into the next element in the output vector. Since each and every value of vec(i) is added to the running sum, this new sum is stored in the outvec(i).

1994_Illustration of Preallocating a Vector.png

Though initializing the output vector outvec to all zeros is not strictly essential, it greatly improves the efficiency of the function. Initializing this vector to all the zeros with similar size as the input argument preallocates that much memory for the outvec. Then, each element is changed in the loop to its right value. On the other hand, when building a vector up one element at a time, as in the earlier illustration, the MATLAB has to find a new memory each time the vector is extended.

The MATLAB has many other functions which work with vectors. 

Posted Date: 10/19/2012 3:39:18 AM | Location : United States







Related Discussions:- Illustration of preallocating a vector, Assignment Help, Ask Question on Illustration of preallocating a vector, Get Answer, Expert's Help, Illustration of preallocating a vector Discussions

Write discussion on Illustration of preallocating a vector
Your posts are moderated
Related Questions
Use polyval to evaluate the derivative at xder. This will be the % slope of the tangent line, "a" (general form of a line: y = ax + b). % 4. Calculate the intercept, b, of t

Interchange rows : for illustration interchanging rows ri and rj is written as

Function cirarea - Anonymous functions: The function handle name is cirarea. The one argument is passed to the input argument radius. The body of the function is an expression

Vector operations: As vectors are special cases of matrices, the matrix operations elaborated (addition, subtraction, multiplication, scalar multiplication, transpose) work on

Passing Structures to Functions: The whole structure can be passed to a function, or separate fields can be passed. For illustration, here are the two distinct versions of a f

I have a vector of X, one for Y , one for x-direction velocity U and one for y-direction velocity V. they are at same size. How can I plot streamline of that flow? I follow all exa

Illustration sorting vectors of structures: This function sorts the structures depend only on the price field. A more common function is shown next, that receives a string whi

str2num function - String: The function str2num does the opposite; it takes the string in which a number is stored and converts it to the type double: >> num = str2num('123.

I dont know how to input different videos on matlab program

Binary Search: The binary search supposes that the vector has been sorted first. The algorithm is just similar to the way it works whenever looking for a name in a phone direc