Selecting specific values from an array based on a defined condition

Question

SB 2019-9-25

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https://ww2.mathworks.cn/matlabcentral/answers/482150-selecting-specific-values-from-an-array-based-on-a-defined-condition

评论： SB 2019-9-25

采纳的回答： Fabio Freschi

I have the following array:

d = [0,100,-100];

m = 300;

I want to select certain values of array d as follows:

d(0<=m+d<=300);

So i want to select all the d values where m+d is beween 0 and 300 with both ends included. The result should look like [0,-100] and 100 should be excluded since it is out the defined range. However, I am getting d to be [0,100,-100]. Please let me know where I went wrong.

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Answer 1

Fabio Freschi 2019-9-25

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https://ww2.mathworks.cn/matlabcentral/answers/482150-selecting-specific-values-from-an-array-based-on-a-defined-condition#answer_393526

编辑：Fabio Freschi 2019-9-25

在 MATLAB Online 中打开

d+m is not scalar: use a single & for logical AND

d(d+m >= 0 & d+m <= 300)

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SB 2019-9-25

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Answer 2

Johannes Fischer 2019-9-25

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https://ww2.mathworks.cn/matlabcentral/answers/482150-selecting-specific-values-from-an-array-based-on-a-defined-condition#answer_393523

编辑：Johannes Fischer 2019-9-25

在 MATLAB Online 中打开

Th logical expression

0 <= m+d <= 300

is not interpreted by Matlab as you think it is. It rather is interpreted as

(0 <= m+d) <= 300

where the expression in brackets results in logical 0 and 1 values which all are below 300, which in turn results in logical 1 at each position. What you want is a combination of both cases

d(0 <= m+d && m+d <= 300);