Plotting Reciprocal of a Complex inequality












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We have a complex inequality $|z-r|leq{sqrt{r}}$. (${r>0}$ is a real constant number and $z$ is a variable complex number). Now we want to find the plot of $f(z) = 1/z$ where $z$ are the answers of above inequality. i.e. we want to find plot of: $|1/z-r|leq sqrt{r}$ $~~~$



I know that the first one is the plot of a circle with Radius $=sqrt r$ and center is $r + 0 i$. (All the point inside and on the perimeter of circle).
But I don't know what to do with the reciprocal of $z$ in $|1/z-r|leq sqrt{r}$ .










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    We have a complex inequality $|z-r|leq{sqrt{r}}$. (${r>0}$ is a real constant number and $z$ is a variable complex number). Now we want to find the plot of $f(z) = 1/z$ where $z$ are the answers of above inequality. i.e. we want to find plot of: $|1/z-r|leq sqrt{r}$ $~~~$



    I know that the first one is the plot of a circle with Radius $=sqrt r$ and center is $r + 0 i$. (All the point inside and on the perimeter of circle).
    But I don't know what to do with the reciprocal of $z$ in $|1/z-r|leq sqrt{r}$ .










    share|cite|improve this question

























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      We have a complex inequality $|z-r|leq{sqrt{r}}$. (${r>0}$ is a real constant number and $z$ is a variable complex number). Now we want to find the plot of $f(z) = 1/z$ where $z$ are the answers of above inequality. i.e. we want to find plot of: $|1/z-r|leq sqrt{r}$ $~~~$



      I know that the first one is the plot of a circle with Radius $=sqrt r$ and center is $r + 0 i$. (All the point inside and on the perimeter of circle).
      But I don't know what to do with the reciprocal of $z$ in $|1/z-r|leq sqrt{r}$ .










      share|cite|improve this question













      We have a complex inequality $|z-r|leq{sqrt{r}}$. (${r>0}$ is a real constant number and $z$ is a variable complex number). Now we want to find the plot of $f(z) = 1/z$ where $z$ are the answers of above inequality. i.e. we want to find plot of: $|1/z-r|leq sqrt{r}$ $~~~$



      I know that the first one is the plot of a circle with Radius $=sqrt r$ and center is $r + 0 i$. (All the point inside and on the perimeter of circle).
      But I don't know what to do with the reciprocal of $z$ in $|1/z-r|leq sqrt{r}$ .







      complex-numbers graphing-functions






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      asked Nov 28 '18 at 20:10









      amir na

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          1 Answer
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          Let $D$ be the unit disc, then your original inequality is satisfied by is the set
          $$
          r + zsqrt{r}, quad z in D
          $$

          and the inverse would be
          $$
          frac{1}{r+zsqrt{r}}, quad z in D.
          $$






          share|cite|improve this answer





















          • Can you say what will be the shape of $frac{1}{r+zsqrt{r}}, quad z in D$ if we graph it? The question is maybe "what is reciprocal of a circle?".
            – amir na
            Nov 28 '18 at 20:19












          • @amirna why don't you do some work on this problem as well? Map out the image of the 4 extremes of the circle under the transformation and perhaps you will get some idea
            – gt6989b
            Nov 28 '18 at 20:21











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          1 Answer
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          1 Answer
          1






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          active

          oldest

          votes









          1














          Let $D$ be the unit disc, then your original inequality is satisfied by is the set
          $$
          r + zsqrt{r}, quad z in D
          $$

          and the inverse would be
          $$
          frac{1}{r+zsqrt{r}}, quad z in D.
          $$






          share|cite|improve this answer





















          • Can you say what will be the shape of $frac{1}{r+zsqrt{r}}, quad z in D$ if we graph it? The question is maybe "what is reciprocal of a circle?".
            – amir na
            Nov 28 '18 at 20:19












          • @amirna why don't you do some work on this problem as well? Map out the image of the 4 extremes of the circle under the transformation and perhaps you will get some idea
            – gt6989b
            Nov 28 '18 at 20:21
















          1














          Let $D$ be the unit disc, then your original inequality is satisfied by is the set
          $$
          r + zsqrt{r}, quad z in D
          $$

          and the inverse would be
          $$
          frac{1}{r+zsqrt{r}}, quad z in D.
          $$






          share|cite|improve this answer





















          • Can you say what will be the shape of $frac{1}{r+zsqrt{r}}, quad z in D$ if we graph it? The question is maybe "what is reciprocal of a circle?".
            – amir na
            Nov 28 '18 at 20:19












          • @amirna why don't you do some work on this problem as well? Map out the image of the 4 extremes of the circle under the transformation and perhaps you will get some idea
            – gt6989b
            Nov 28 '18 at 20:21














          1












          1








          1






          Let $D$ be the unit disc, then your original inequality is satisfied by is the set
          $$
          r + zsqrt{r}, quad z in D
          $$

          and the inverse would be
          $$
          frac{1}{r+zsqrt{r}}, quad z in D.
          $$






          share|cite|improve this answer












          Let $D$ be the unit disc, then your original inequality is satisfied by is the set
          $$
          r + zsqrt{r}, quad z in D
          $$

          and the inverse would be
          $$
          frac{1}{r+zsqrt{r}}, quad z in D.
          $$







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 28 '18 at 20:16









          gt6989b

          33.1k22452




          33.1k22452












          • Can you say what will be the shape of $frac{1}{r+zsqrt{r}}, quad z in D$ if we graph it? The question is maybe "what is reciprocal of a circle?".
            – amir na
            Nov 28 '18 at 20:19












          • @amirna why don't you do some work on this problem as well? Map out the image of the 4 extremes of the circle under the transformation and perhaps you will get some idea
            – gt6989b
            Nov 28 '18 at 20:21


















          • Can you say what will be the shape of $frac{1}{r+zsqrt{r}}, quad z in D$ if we graph it? The question is maybe "what is reciprocal of a circle?".
            – amir na
            Nov 28 '18 at 20:19












          • @amirna why don't you do some work on this problem as well? Map out the image of the 4 extremes of the circle under the transformation and perhaps you will get some idea
            – gt6989b
            Nov 28 '18 at 20:21
















          Can you say what will be the shape of $frac{1}{r+zsqrt{r}}, quad z in D$ if we graph it? The question is maybe "what is reciprocal of a circle?".
          – amir na
          Nov 28 '18 at 20:19






          Can you say what will be the shape of $frac{1}{r+zsqrt{r}}, quad z in D$ if we graph it? The question is maybe "what is reciprocal of a circle?".
          – amir na
          Nov 28 '18 at 20:19














          @amirna why don't you do some work on this problem as well? Map out the image of the 4 extremes of the circle under the transformation and perhaps you will get some idea
          – gt6989b
          Nov 28 '18 at 20:21




          @amirna why don't you do some work on this problem as well? Map out the image of the 4 extremes of the circle under the transformation and perhaps you will get some idea
          – gt6989b
          Nov 28 '18 at 20:21


















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