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2013-02-27 11:00:23 +0200 | asked a question | How to substitute realpart and imagpart after conversion to rectform? Hello, I need to split some complicated expression into real and imaginary part, and I use function "rectform()" to do it. Then I want to plot just the imaginary part of the expression, and it seems obvious to substitute zero in place of real part. However, the substitution does not work. Here is a minimal example, which reproduces this behavior. I want to substitute $\Re [A]$ with "$x$": Then we try to substitute $\Re[x] \to x$: Then I try to use interface to maxima: As you can see, maxima replaces $A$ with $x$ in the whole expression. E.g., if $x=0$, then after the substitution the whole expression is zero, not just the real part. How to do the substitution? Are there any workarounds? |
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2013-02-23 17:40:03 +0200 | commented answer | Bug with absolute value of a complex variable? Thank you, it works. As I see, the only difference here is that you used function "assume", and it had effect. But if you specify domain at the definition of variable, it doesn't work. Is it present on the bug tracker? |
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2013-02-23 15:38:37 +0200 | asked a question | Bug with absolute value of a complex variable? I perform some analytic calculations involving complex number, in particular complex electric field amplitude. I was quite shocked when I discovered how SAGE handles complex variables. So, I define a new variable "A" and explicitly say that it is complex. Then I want to find the absolute value of this variable, which is $AA^* = |A|^2$. Furthermore we check, if $AA = |A|^2 = AA^*$, and it does! But this is obviously WRONG, since if I assign some number to $A$, then the last test does not result in zero: Am I understanding/doing something wrong? |