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solve false answer with a exponential equation

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franco otaola
franco otaola on 12 Oct 2016
Closed: MATLAB Answer Bot on 20 Aug 2021
hello i am trying to solve an equation and each time that i try to solve it with the matlab it keeps giving me a false value it doenst give any error or anything... here is the code
syms x
Cf=1;
C_0=10;
M=1.1*1350;
m=155;
thao=M/m;
C=C_0*exp(-x/thao)-Cf;
solve(C,x)
and it keeps giving me the
ans=(297*log(10))/31 %log(10)=1 so, 297/37 that it is aprox 9.56 when the real value is 22.06 aprox
obviusly false. i couldnt find any error or problem in the code. anyone had the same problem?

Answers (1)

Walter Roberson
Walter Roberson on 12 Oct 2016
log(10) is not 1. log() is natural log. The calculation gives the value you expect. Use vpa() or double() to see the decimal equivalent.
  2 Comments
Walter Roberson
Walter Roberson on 12 Oct 2016
I looked around a few months ago, and I could not find any programming language which used ln() for natural log. All of the major languages I checked used log()

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