拉氏反变换出现一堆表达式，出不来结果。

求大神帮助指点，该怎么才能逆变换成功呢

ilaplace((10000000000*(22090000000000*s^3 + 47000000000*s^2 + 23525002209*s + 25000000))/(220900000000000000000000*s^4 + 470000000000000000000*s^3 + 470250044180000000000*s^2 + 500000047000000000*s + 249999953025002209))

ans =

7812500000000000*symsum(exp(t*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k))/(16*(2753906250000000000*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^2 + 1725781250000000122880*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^3 + 1836914235078125056*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k) + 976562591796875)), k, 1, 4) + 7351563190312500000*symsum((exp(root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)*t)*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k))/(16*(1836914235078125056*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k) + 2753906250000000000*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^2 + 1725781250000000122880*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^3 + 976562591796875)), k, 1, 4) + 14687500000000000000*symsum((exp(t*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k))*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^2)/(16*(2753906250000000000*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^2 + 1725781250000000122880*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^3 + 1836914235078125056*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k) + 976562591796875)), k, 1, 4) + 6903125000000000000000*symsum((exp(t*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k))*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^3)/(16*(2753906250000000000*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^2 + 1725781250000000122880*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^3 + 1836914235078125056*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k) + 976562591796875)), k, 1, 4)

Answer 1

[wytxqerd]

这也不算失败吧，只不过很多数值，因为涉及到求解一元四次方程，软件就写成"调用该方程的第几个根"的形式了，因为如果代入求根公式的话，表达式一般会更长。

使用vpa( ans, 2 )是可以查看将所有符号数值都转换为一定精度数值的表达式

得到

exp(-5.3e-4*t)*cos(0.033*t)*(0.25 + 4.1e-3i) + exp(-5.3e-4*t)*cos(0.033*t)*(0.25 - 4.1e-3i) + exp(-5.3e-4*t)*cos(0.033*t)*(0.25 - 4.1e-3i) + exp(-5.3e-4*t)*cos(0.033*t)*(0.25 + 4.1e-3i) + exp(-5.3e-4*t)*sin(0.033*t)*(4.1e-3 - 0.25i) + exp(-5.3e-4*t)*sin(0.033*t)*(4.1e-3 + 0.25i) + exp(-5.3e-4*t)*sin(0.033*t)*(4.1e-3 + 0.25i) + exp(-5.3e-4*t)*sin(0.033*t)*(4.1e-3 - 0.25i)

另外，如果用Mathematica的话，能求得