blocks|key|2132603|text|编辑：正如@MarkDickinson指出的，你可以使用-sign(min(x,+y))|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|2132604|num+*=+-1+*+sign(min(x,+y))|code-block|syntax|javascript|2132605|然后：|2132606|如果两个结果都为正，则结果为-1.|2132607|If，其中至少有一个为负，则结果为1.|unordered-list-item|2132608|2132609|entityMap^0|0|2|S|G|0|0|0|E|2|0|H|1|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|D]]|E|@]|F|$]]|$1|G|3|H|5|I|7|10|8|@]|E|@]|F|$J|K]]|$1|L|3|M|5|6|7|11|8|@]|E|@]|F|$]]|$1|N|3|O|5|6|7|12|8|@$9|13|A|14|B|D]]|E|@]|F|$]]|$1|P|3|Q|5|R|7|15|8|@$9|16|A|17|B|D]]|E|@]|F|$]]|$1|S|3|-4|5|6|7|18|8|@]|E|@]|F|$]]|$1|T|3|-4|5|6|7|19|8|@]|E|@]|F|$]]]|U|$]]

EDIT: As @MarkDickinson pointed out, you can use <code>-sign(min(x, y))</code>:

<pre><code>num *= -1 * sign(min(x, y))
</code></pre>

Then:

<ul>
<li>If both are positive - the result is <code>-1</code>.</li>
<li>If at least one of them is negative - the result is <code>1</code>.</li>
</ul>

blocks|key|3545720|text|您可以使用ternary+operator|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3545721|3545722|在数学中，三元运算是n=+3的n元运算。集合A上的三元运算取A的任意给定的三个元素，并将它们组合成A的单个元素。三元运算符是一个带有三个参数的运算符。第一个参数是比较参数，第二个是真比较的结果，第三个是假比较的结果。|blockquote|3545723|3545724|3545725|例如，在C%2B%2B中，它将显示为：|3545726|num+*=+(x>0+&&+y>0)+?+-1+:+1;|code-block|syntax|javascript|3545727|它代表(condition)+?+if_true+:+if_false。|style|CODE|3545728|这也适用于特殊情况x和/或y求值为0的情况，因为它不会反转符号。注sign(0)通常被定义为0，这不是您所说的您想要的行为。|3545729|entityMap|0|LINK|mutability|MUTABLE|url|https://en.wikipedia.org/wiki/Ternary_operation|1|https://docs.scipy.org/doc/numpy/reference/generated/numpy.sign.html^0|5|G|0|0|0|0|0|0|0|0|3|W|0|X|7|1|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@$A|17|B|18|1|19]]|C|$]]|$1|D|3|-4|5|6|7|1A|8|@]|9|@]|C|$]]|$1|E|3|F|5|G|7|1B|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|1C|8|@]|9|@]|C|$]]|$1|I|3|-4|5|6|7|1D|8|@]|9|@]|C|$]]|$1|J|3|K|5|6|7|1E|8|@]|9|@]|C|$]]|$1|L|3|M|5|N|7|1F|8|@]|9|@]|C|$O|P]]|$1|Q|3|R|5|6|7|1G|8|@$A|1H|B|1I|S|T]]|9|@]|C|$]]|$1|U|3|V|5|6|7|1J|8|@]|9|@$A|1K|B|1L|1|1M]]|C|$]]|$1|W|3|-4|5|6|7|1N|8|@]|9|@]|C|$]]]|X|$Y|$5|Z|10|11|C|$12|13]]|14|$5|Z|10|11|C|$12|15]]]]

You can use a <a href="https://en.wikipedia.org/wiki/Ternary_operation" rel="nofollow noreferrer">ternary operator</a>:

<blockquote>
 In mathematics, a ternary operation is an n-ary operation with n = 3. A ternary operation on a set A takes any given three elements of A and combines them to form a single element of A. The ternary operator is an operator that takes three arguments. The first argument is a comparison argument, the second is the result upon a true comparison, and the third is the result upon a false comparison.
</blockquote>

For example in C++ it would read:

<pre><code>num *= (x&gt;0 &amp;&amp; y&gt;0) ? -1 : 1;
</code></pre>

which represents <code>(condition) ? if_true : if_false</code>.

This would also work for the special case x and/or y evaluate to 0, since it would not flip the sign. Note <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.sign.html" rel="nofollow noreferrer">sign(0)</a> is usually defined as 0 and that is not the behaviour you said you wanted.

I am looking for a mathematical expression to flip the sign of a number if two other numbers are positive.

This is easy for a single condition <code>x &gt; 0</code>, in which case I'd do <code>num *= sign(x)</code>.

But how to do that with two conditions <code>x &gt; 0</code> and <code>y &gt; 0</code>? This is incorrect:

<pre><code>num *= sign(-x) * sign(-y)
</code></pre>

(as it flips the sign also if both <code>x &lt; 0</code> and <code>y &lt; 0</code>, which I don't want).

I'd come up with

<pre><code>num *= sgn(-x) ** H(y)
</code></pre>

and

<pre><code>num *= 1 - 2 * H(x) * H(y)
</code></pre>

where <code>H</code> is the Heavyside step function, but while that is brief, it's not explicit.

<pre><code>num *= (-1)^(H(x) * H(y))
</code></pre>

is a bit better, but can we go nicer/shorter/more explicit?

This question is not specific to a particular programming language - actually, it's not about programming at all, so using an <code>if</code> is not exactly what I want. I am looking for something like an in-line if for mathematicians, and I thought I'd find people with the best mindsets for this question in a programmers' forum... please tell me I was right ;)

How to flip the sign of a number if two conditions are true?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在寻找一个数学表达式来反转一个数字的符号，如果其他两个数字是正的。对于单个条件x > 0，这很容易，在这种情况下，我将执行num *= sign(x)。但是如何在有两个条件x > 0和y > 0的情况下做到这一点呢？这是不正确的：num *= sign(-x) * sign(-y)(如果同时使用x < 0和y < ...

问如果两个条件都为真，如何反转数字的符号？
EN

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问如果两个条件都为真，如何反转数字的符号？EN