Make a float using integers [on hold]











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0
down vote

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I want to make a floating point number that has only one decimal point.
I have separate integers for both side.
Ex:



int n1 = 8;



int n2 = 2;



I want to make 8.2 as float value using separate integers.
Please give me a solution.










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put on hold as off-topic by Juraj, sempaiscuba, per1234, gre_gor, Greenonline Dec 1 at 2:43


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question does not appear to be about Arduino, within the scope defined in the help center." – Juraj, sempaiscuba, per1234, gre_gor, Greenonline

If this question can be reworded to fit the rules in the help center, please edit the question.

















    up vote
    0
    down vote

    favorite












    I want to make a floating point number that has only one decimal point.
    I have separate integers for both side.
    Ex:



    int n1 = 8;



    int n2 = 2;



    I want to make 8.2 as float value using separate integers.
    Please give me a solution.










    share|improve this question













    put on hold as off-topic by Juraj, sempaiscuba, per1234, gre_gor, Greenonline Dec 1 at 2:43


    This question appears to be off-topic. The users who voted to close gave this specific reason:


    • "This question does not appear to be about Arduino, within the scope defined in the help center." – Juraj, sempaiscuba, per1234, gre_gor, Greenonline

    If this question can be reworded to fit the rules in the help center, please edit the question.















      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      I want to make a floating point number that has only one decimal point.
      I have separate integers for both side.
      Ex:



      int n1 = 8;



      int n2 = 2;



      I want to make 8.2 as float value using separate integers.
      Please give me a solution.










      share|improve this question













      I want to make a floating point number that has only one decimal point.
      I have separate integers for both side.
      Ex:



      int n1 = 8;



      int n2 = 2;



      I want to make 8.2 as float value using separate integers.
      Please give me a solution.







      arduino-uno variables float






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 30 at 9:25









      user119o

      255




      255




      put on hold as off-topic by Juraj, sempaiscuba, per1234, gre_gor, Greenonline Dec 1 at 2:43


      This question appears to be off-topic. The users who voted to close gave this specific reason:


      • "This question does not appear to be about Arduino, within the scope defined in the help center." – Juraj, sempaiscuba, per1234, gre_gor, Greenonline

      If this question can be reworded to fit the rules in the help center, please edit the question.




      put on hold as off-topic by Juraj, sempaiscuba, per1234, gre_gor, Greenonline Dec 1 at 2:43


      This question appears to be off-topic. The users who voted to close gave this specific reason:


      • "This question does not appear to be about Arduino, within the scope defined in the help center." – Juraj, sempaiscuba, per1234, gre_gor, Greenonline

      If this question can be reworded to fit the rules in the help center, please edit the question.






















          2 Answers
          2






          active

          oldest

          votes

















          up vote
          4
          down vote



          accepted










          Seems too simple:



          float x = n1 + n2 * 0.1;


          Is there a trick?



          Edit: The method proposed by Michel Keijzers, namely



          float x = n1 + n2 / 10.0;


          (I removed the redundant casts) can be slightly more accurate, but takes
          longer to compute, because division is significantly slower than
          multiplication on the Uno. Computing n2/10.0 always yields the
          correctly rounded result, namely the float that best approximates the
          exact mathematical result. On the other hand, n2*0.1 involves two
          rounding operations: one at compile time, in the representation of 0.1
          (which is not an exact float), another at run time, which rounds the
          result of the multiplication. If n2 is between 0 and 8, you end up
          getting the correctly rounded result anyway, just as with n2/10.0.
          However, if n2 is 9, then





          • n2*0.1 yields 0.900000035762786865234375 (error ≈ 3.6e-8)


          • n2/10.0 yields 0.89999997615814208984375 (error ≈ -2.4e-8)


          The former carries a rounding error 1.5 larger than the latter.






          share|improve this answer























          • Thanks. Its a real trick.
            – user119o
            Nov 30 at 9:36


















          up vote
          2
          down vote













          float x = (float) n1 + (float) (n2 / 10.0);


          This works only if the value of n2 has 1 digit. Otherwise the following make it smaller until n2 gets below 1.0:



          float x = (float) n1;

          float f2 = (float) n2;
          while (f2 >= 1.0)
          {
          f2 /= 10.0;
          }
          x = n1 + f2;





          share|improve this answer



















          • 1




            Its working without problem. Thanks
            – user119o
            Nov 30 at 9:43


















          2 Answers
          2






          active

          oldest

          votes








          2 Answers
          2






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes








          up vote
          4
          down vote



          accepted










          Seems too simple:



          float x = n1 + n2 * 0.1;


          Is there a trick?



          Edit: The method proposed by Michel Keijzers, namely



          float x = n1 + n2 / 10.0;


          (I removed the redundant casts) can be slightly more accurate, but takes
          longer to compute, because division is significantly slower than
          multiplication on the Uno. Computing n2/10.0 always yields the
          correctly rounded result, namely the float that best approximates the
          exact mathematical result. On the other hand, n2*0.1 involves two
          rounding operations: one at compile time, in the representation of 0.1
          (which is not an exact float), another at run time, which rounds the
          result of the multiplication. If n2 is between 0 and 8, you end up
          getting the correctly rounded result anyway, just as with n2/10.0.
          However, if n2 is 9, then





          • n2*0.1 yields 0.900000035762786865234375 (error ≈ 3.6e-8)


          • n2/10.0 yields 0.89999997615814208984375 (error ≈ -2.4e-8)


          The former carries a rounding error 1.5 larger than the latter.






          share|improve this answer























          • Thanks. Its a real trick.
            – user119o
            Nov 30 at 9:36















          up vote
          4
          down vote



          accepted










          Seems too simple:



          float x = n1 + n2 * 0.1;


          Is there a trick?



          Edit: The method proposed by Michel Keijzers, namely



          float x = n1 + n2 / 10.0;


          (I removed the redundant casts) can be slightly more accurate, but takes
          longer to compute, because division is significantly slower than
          multiplication on the Uno. Computing n2/10.0 always yields the
          correctly rounded result, namely the float that best approximates the
          exact mathematical result. On the other hand, n2*0.1 involves two
          rounding operations: one at compile time, in the representation of 0.1
          (which is not an exact float), another at run time, which rounds the
          result of the multiplication. If n2 is between 0 and 8, you end up
          getting the correctly rounded result anyway, just as with n2/10.0.
          However, if n2 is 9, then





          • n2*0.1 yields 0.900000035762786865234375 (error ≈ 3.6e-8)


          • n2/10.0 yields 0.89999997615814208984375 (error ≈ -2.4e-8)


          The former carries a rounding error 1.5 larger than the latter.






          share|improve this answer























          • Thanks. Its a real trick.
            – user119o
            Nov 30 at 9:36













          up vote
          4
          down vote



          accepted







          up vote
          4
          down vote



          accepted






          Seems too simple:



          float x = n1 + n2 * 0.1;


          Is there a trick?



          Edit: The method proposed by Michel Keijzers, namely



          float x = n1 + n2 / 10.0;


          (I removed the redundant casts) can be slightly more accurate, but takes
          longer to compute, because division is significantly slower than
          multiplication on the Uno. Computing n2/10.0 always yields the
          correctly rounded result, namely the float that best approximates the
          exact mathematical result. On the other hand, n2*0.1 involves two
          rounding operations: one at compile time, in the representation of 0.1
          (which is not an exact float), another at run time, which rounds the
          result of the multiplication. If n2 is between 0 and 8, you end up
          getting the correctly rounded result anyway, just as with n2/10.0.
          However, if n2 is 9, then





          • n2*0.1 yields 0.900000035762786865234375 (error ≈ 3.6e-8)


          • n2/10.0 yields 0.89999997615814208984375 (error ≈ -2.4e-8)


          The former carries a rounding error 1.5 larger than the latter.






          share|improve this answer














          Seems too simple:



          float x = n1 + n2 * 0.1;


          Is there a trick?



          Edit: The method proposed by Michel Keijzers, namely



          float x = n1 + n2 / 10.0;


          (I removed the redundant casts) can be slightly more accurate, but takes
          longer to compute, because division is significantly slower than
          multiplication on the Uno. Computing n2/10.0 always yields the
          correctly rounded result, namely the float that best approximates the
          exact mathematical result. On the other hand, n2*0.1 involves two
          rounding operations: one at compile time, in the representation of 0.1
          (which is not an exact float), another at run time, which rounds the
          result of the multiplication. If n2 is between 0 and 8, you end up
          getting the correctly rounded result anyway, just as with n2/10.0.
          However, if n2 is 9, then





          • n2*0.1 yields 0.900000035762786865234375 (error ≈ 3.6e-8)


          • n2/10.0 yields 0.89999997615814208984375 (error ≈ -2.4e-8)


          The former carries a rounding error 1.5 larger than the latter.







          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited Nov 30 at 11:33

























          answered Nov 30 at 9:30









          Edgar Bonet

          23.6k22344




          23.6k22344












          • Thanks. Its a real trick.
            – user119o
            Nov 30 at 9:36


















          • Thanks. Its a real trick.
            – user119o
            Nov 30 at 9:36
















          Thanks. Its a real trick.
          – user119o
          Nov 30 at 9:36




          Thanks. Its a real trick.
          – user119o
          Nov 30 at 9:36










          up vote
          2
          down vote













          float x = (float) n1 + (float) (n2 / 10.0);


          This works only if the value of n2 has 1 digit. Otherwise the following make it smaller until n2 gets below 1.0:



          float x = (float) n1;

          float f2 = (float) n2;
          while (f2 >= 1.0)
          {
          f2 /= 10.0;
          }
          x = n1 + f2;





          share|improve this answer



















          • 1




            Its working without problem. Thanks
            – user119o
            Nov 30 at 9:43















          up vote
          2
          down vote













          float x = (float) n1 + (float) (n2 / 10.0);


          This works only if the value of n2 has 1 digit. Otherwise the following make it smaller until n2 gets below 1.0:



          float x = (float) n1;

          float f2 = (float) n2;
          while (f2 >= 1.0)
          {
          f2 /= 10.0;
          }
          x = n1 + f2;





          share|improve this answer



















          • 1




            Its working without problem. Thanks
            – user119o
            Nov 30 at 9:43













          up vote
          2
          down vote










          up vote
          2
          down vote









          float x = (float) n1 + (float) (n2 / 10.0);


          This works only if the value of n2 has 1 digit. Otherwise the following make it smaller until n2 gets below 1.0:



          float x = (float) n1;

          float f2 = (float) n2;
          while (f2 >= 1.0)
          {
          f2 /= 10.0;
          }
          x = n1 + f2;





          share|improve this answer














          float x = (float) n1 + (float) (n2 / 10.0);


          This works only if the value of n2 has 1 digit. Otherwise the following make it smaller until n2 gets below 1.0:



          float x = (float) n1;

          float f2 = (float) n2;
          while (f2 >= 1.0)
          {
          f2 /= 10.0;
          }
          x = n1 + f2;






          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited Nov 30 at 9:44

























          answered Nov 30 at 9:31









          Michel Keijzers

          6,26841737




          6,26841737








          • 1




            Its working without problem. Thanks
            – user119o
            Nov 30 at 9:43














          • 1




            Its working without problem. Thanks
            – user119o
            Nov 30 at 9:43








          1




          1




          Its working without problem. Thanks
          – user119o
          Nov 30 at 9:43




          Its working without problem. Thanks
          – user119o
          Nov 30 at 9:43



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