dlmwrite(filename,file,'delimiter',',','newline','pc','precision','%.7f');

設定精度就不會將科學計數法的資料寫入到txt檔案中去。

matlab中保留有效位數

通過 vpa可以僅保留有效位數

vpaVariableprecisionarithmetic.
R=vpa(S)numericallyevaluateseachelementofthedoublematrix
SusingvariableprecisionfloatingpointarithmeticwithDdecimal
digitaccuracy,whereDisthecurrentsettingofDIGITS.

TheresultingRisaSYM.

vpa(S,D)usesDdigits,insteadofthecurrentsettingofDIGITS.
DisanintegerortheSYMrepresentationofanumber.

Itisimportanttoavoidtheevaluationofanexpressionusingdouble
precisionfloatingpointarithmeticbeforeitispassedtovpa.
Forexample,
phi=vpa((1+sqrt(5))/2)
firstcomputesa16-digitapproximationtothegoldenratio,then
convertsthatapproximationtoonewithddigits,wheredisthecurrent
settingofDIGITS.Togetfullprecision,useunevaluatedstringor
symbolicarguments,
phi=vpa('(1+sqrt(5))/2')
or
s=sym('sqrt(5)')
phi=vpa((1+s)/2);

Additionalexamples:
vpa(pi,780)showssixconsecutive9'sneardigit770inthe
decimalexpansionofpi.

vpa(hilb(2),5)returns

[1.,.50000]
[.50000,.33333]