matlab求:d∫上限(lnx)下限0的√(1+t^4)dt/dx为什么成了这样?是我的matlab设置出了什么问题吗?>> syms t x>> f=sqrt(1+t^4);>> diff(int(f,t,0,log(x)),x)ans =(1/12-1/12*i)*(1/x*2^(1/2)+5*log(x)^4*2^(1/2)/x+(2+3*i)/x*2^(1/2)+
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![matlab求:d∫上限(lnx)下限0的√(1+t^4)dt/dx为什么成了这样?是我的matlab设置出了什么问题吗?>> syms t x>> f=sqrt(1+t^4);>> diff(int(f,t,0,log(x)),x)ans =(1/12-1/12*i)*(1/x*2^(1/2)+5*log(x)^4*2^(1/2)/x+(2+3*i)/x*2^(1/2)+](/uploads/image/z/5937055-7-5.jpg?t=matlab%E6%B1%82%3Ad%E2%88%AB%E4%B8%8A%E9%99%90%EF%BC%88lnx%EF%BC%89%E4%B8%8B%E9%99%900%E7%9A%84%E2%88%9A%EF%BC%881%2Bt%5E4%EF%BC%89dt%2Fdx%E4%B8%BA%E4%BB%80%E4%B9%88%E6%88%90%E4%BA%86%E8%BF%99%E6%A0%B7%3F%E6%98%AF%E6%88%91%E7%9A%84matlab%E8%AE%BE%E7%BD%AE%E5%87%BA%E4%BA%86%E4%BB%80%E4%B9%88%E9%97%AE%E9%A2%98%E5%90%97%3F%3E%3E+syms+t+x%3E%3E+f%3Dsqrt%281%2Bt%5E4%29%3B%3E%3E+diff%28int%28f%2Ct%2C0%2Clog%28x%29%29%2Cx%29ans+%3D%281%2F12-1%2F12%2Ai%29%2A%281%2Fx%2A2%5E%281%2F2%29%2B5%2Alog%28x%29%5E4%2A2%5E%281%2F2%29%2Fx%2B%282%2B3%2Ai%29%2Fx%2A2%5E%281%2F2%29%2B)
matlab求:d∫上限(lnx)下限0的√(1+t^4)dt/dx为什么成了这样?是我的matlab设置出了什么问题吗?>> syms t x>> f=sqrt(1+t^4);>> diff(int(f,t,0,log(x)),x)ans =(1/12-1/12*i)*(1/x*2^(1/2)+5*log(x)^4*2^(1/2)/x+(2+3*i)/x*2^(1/2)+
matlab求:d∫上限(lnx)下限0的√(1+t^4)dt/dx为什么成了这样?是我的matlab设置出了什么问题吗?
>> syms t x
>> f=sqrt(1+t^4);
>> diff(int(f,t,0,log(x)),x)
ans =
(1/12-1/12*i)*(1/x*2^(1/2)+5*log(x)^4*2^(1/2)/x+(2+3*i)/x*2^(1/2)+5*i*log(x)^4*2^(1/2)/x-4*i/(1-i*log(x)^2)^(1/2)*(1+i*log(x)^2)^(1/2)*EllipticF((1/2+1/2*i)*log(x)*2^(1/2),i)*log(x)/x+4*i*(1-i*log(x)^2)^(1/2)/(1+i*log(x)^2)^(1/2)*EllipticF((1/2+1/2*i)*log(x)*2^(1/2),i)*log(x)/x)*2^(1/2)/(1+log(x)^4)^(1/2)+(-1/6+1/6*i)*(log(x)*2^(1/2)+log(x)^5*2^(1/2)+i*log(x)*2^(1/2)+i*log(x)^5*2^(1/2)+4*(1-i*log(x)^2)^(1/2)*(1+i*log(x)^2)^(1/2)*EllipticF((1/2+1/2*i)*log(x)*2^(1/2),i))*2^(1/2)/(1+log(x)^4)^(3/2)*log(x)^3/x
matlab求:d∫上限(lnx)下限0的√(1+t^4)dt/dx为什么成了这样?是我的matlab设置出了什么问题吗?>> syms t x>> f=sqrt(1+t^4);>> diff(int(f,t,0,log(x)),x)ans =(1/12-1/12*i)*(1/x*2^(1/2)+5*log(x)^4*2^(1/2)/x+(2+3*i)/x*2^(1/2)+
本题手算也是十分简单的吧?为什么要用matlab呢,我不知道matlab是否会做这种变上限积分的导数,你这样写肯定是不行的,这样的话,matlab会先去算那个积分,就会算出一堆复杂的东西,算完积分后才会去求导,而我们人工计算时肯定不会去算积分的,因此这种题建议不要用matlab去算.
这是把简单问题复杂化了,数学软件的化简能力本身就是比较弱的.
回复:那你可以这样啊.用matlab做一个变量替换,将√(1+t^4)中的t换成lnx,然后用matlab求一下lnx的导数,再和刚才的结果乘起来,这不就是用matlab把结果做出来了吗?