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How to evaluate an integral?

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Max
Max 2016-1-30
关闭： MATLAB Answer Bot 2021-8-20
Hello,
I would like to evaluate the following function which includes an integral. The aim is to get sth. like that: Var_beta_hat_direct = a kind of number. But I only get a symbolic expression and not a number.
Does anybody have an idea?
syms t
Var_beta_hat_direct=vpa(10681743549394799937933824491520*exp(int((140737488355328*exp(-8187485477687969/(4398046511104*(20*heaviside(t - 2000) + 40*heaviside(t - 3000) - 390*heaviside(t - 14000) + 330*heaviside(t)))))/8301382342175545, t, 0, 1671787363946201/274877906944)^(4831891999187463/1125899906842624))*exp(8187485477687969/1715238139330560)*((140737488355328*exp(-int((140737488355328*exp(-8187485477687969/(4398046511104*(20*heaviside(t - 2000) + 40*heaviside(t - 3000) - 390*heaviside(t - 14000) + 330*heaviside(t)))))/8301382342175545, t, 0, 1671787363946201/274877906944)^(4831891999187463/1125899906842624))*exp(-8187485477687969/1715238139330560)*int((140737488355328*exp(-8187485477687969/(4398046511104*(20*heaviside(t - 2000) + 40*heaviside(t - 3000) - 390*heaviside(t - 14000) + 330*heaviside(t)))))/8301382342175545, t, 0, 1671787363946201/274877906944)^(3705992092344839/1125899906842624))/8301382342175545 + (690270285598209*log(int((140737488355328*exp(-8187485477687969/(4398046511104*(20*heaviside(t - 2000) + 40*heaviside(t - 3000) - 390*heaviside(t - 14000) + 330*heaviside(t)))))/8301382342175545, t, 0, 1671787363946201/274877906944))*exp(-int((140737488355328*exp(-8187485477687969/(4398046511104*(20*heaviside(t - 2000) + 40*heaviside(t - 3000) - 390*heaviside(t - 14000) + 330*heaviside(t)))))/8301382342175545, t, 0, 1671787363946201/274877906944)^(4831891999187463/1125899906842624))*exp(-8187485477687969/1715238139330560)*int((140737488355328*exp(-8187485477687969/(4398046511104*(20*heaviside(t - 2000) + 40*heaviside(t - 3000) - 390*heaviside(t - 14000) + 330*heaviside(t)))))/8301382342175545, t, 0, 1671787363946201/274877906944)^(3705992092344839/1125899906842624))/9487294105343480 - (690270285598209*log(int((140737488355328*exp(-8187485477687969/(4398046511104*(20*heaviside(t - 2000) + 40*heaviside(t - 3000) - 390*heaviside(t - 14000) + 330*heaviside(t)))))/8301382342175545, t, 0, 1671787363946201/274877906944))*exp(-int((140737488355328*exp(-8187485477687969/(4398046511104*(20*heaviside(t - 2000) + 40*heaviside(t - 3000) - 390*heaviside(t - 14000) + 330*heaviside(t)))))/8301382342175545, t, 0, 1671787363946201/274877906944)^(4831891999187463/1125899906842624))*exp(-8187485477687969/1715238139330560)*int((140737488355328*exp(-8187485477687969/(4398046511104*(20*heaviside(t - 2000) + 40*heaviside(t - 3000) - 390*heaviside(t - 14000) + 330*heaviside(t)))))/8301382342175545, t, 0, 1671787363946201/274877906944)^(4268942045766151/562949953421312))/9487294105343480))

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回答（1 个）

Walter Roberson
Walter Roberson 2016-1-30
All of those int() expressions are exactly the same. Pull that out of the expression and evaluate it and drop the result into the larger expression.
The result is about -2.546320960311438*10^28 by the way.
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Max
Max 2016-1-30
I´m using the R2015b version.
Max
Max 2016-1-30
But you also can test out my code and you´ll see that it´s not working.

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