在编写的结果中有这样的语句
不知道是什么意思
等指教
log :domain error

log :domain error
floating point error:domain
不知道是什么意思

谢谢了

#define pai 3.14159265 #include <math.h>

double max(double x,double y) {double z; if(x>=y) z=x; else z=y; return z; }

double min(double x,double y) {double z; if(x>=y) z=y; else z=x; return z; }

double midu(double x,double y)/*求相对密度*//*x=1+Tm/100,y是相对密度 成功*/ {double z; z=0.942+0.248*x+0.174*y*y+0.0841/(x*x)-0.312*x/y-0.56*exp(-x);/*计算物质的相对密度*/ return z;}

double bire(double x,double y,double z)/*相对密度 温度 油品特性 成功*/ {double m; m=(0.7072+(0.00147-0.000551*x)*y-0.318*x)*(0.055*z+0.35); return m; } /*成功了*/

double redao(double x,double y)/*相对密度 温度 已经成功*/ {double z; z=0.1008*(1-0.00054*y)/x; return z; }

double niandu1(double t)/*温度*//*求渣油的粘度*/ {double a,b,z,c,d; a=18.917279,b=-2.9298204; d=a+b*log(t+273); c=exp(d); z=exp(c)-1.22; return z; }

double niandu2(double t)/*温度*//*求原油的粘度*/ { double a,b,z,c,d; b=-3.87380407; a=22.811425; d=a+b*log(t+273); c=exp(d); z=exp(c)-1.22; return z; }

main() {double max(double x,double y); double min(double x,double y); double midu(double x,double y); double bire(double x,double y,double z); double redao(double x,double y); double niandu1(double t); double niandu2(double t);

float wh=68250, th1=382,wc=175000,tc1=275,A=130,D=0.7,d0=0.025,di=0.02,L=6, At=0.0438,As=0.0525,Ri=0.0005,Ro=0.0001,Dh20=0.919,Dc20=0.850,K=12.5,tc20,th20, C,cpc1,cph1,Xc,Xh,dT1,dT2,dTm,pcm,phm,cpcm,cphm,N1,N2,rd1,rd2, Q,N,Np,Si,u1,Qi,Ai,Rei,Pri,Nui,hi0,Nwi,hi,twi1,Twi,Hi,u2,Qo,Ao,de,Reo,Pro, Nuo,ho0,Nwo,ho,two1,Two,Ho,k,H,Cmin,Cmax,NTU,R,TT,e,tc2,th2,eh,fi,dph,fo,dpc,v,p; int i,n,m; double Tmc,Tmh,twi,two;

cpc1=bire(Dc20,tc1,K); cph1=bire(Dh20,th1,K); C=(wc*cpc1)/(wh*cph1); tc20=20;/*先假定一个温度*/ tc2=300;

for(i=0;fabs(tc2-tc20)>0.1;i++) {tc20=tc2; th20=th1-C*(tc20-tc1); Tmc=(tc1+tc20)/2;/*定性温度*/ Tmh=(th1+th20)/2;

printf("Tmc=%f,Tmh=%f,tc20=%f,th20=%f",Tmc,Tmh,tc20,th20); Xc=1+Tmc/100; Xh=1+Tmh/100;

dT1=th1-th20; dT2=tc20-tc1; dTm=(dT1-dT2)/log(dT1/dT2); printf("Xc=%f,Xh=%f,dT1=%f,dT2=%f,dTm=%f",Xc,Xh,dT1,dT2,dTm);

pcm=midu(Xc,Dc20); phm=midu(Xh,Dh20); cpcm=bire(Dc20,Tmc,K); cphm=bire(Dh20,Tmh,K); N1=niandu1(Tmh); N2=niandu2(Tmc); rd1=redao(Dh20,Tmh); rd2=redao(Dc20,Tmc); printf("pcm=%f,phm=%f,cpcm=%f,cphm=%f,N1=%f,N2=%f,rd1=%f,rd2=%f\n",pcm,phm,cpcm,cphm,N1,N2,rd1,rd2);

/*管内表面传热系数的计算*/

N=277; Np=2;

Si=pai*di*di*N/(Np*4); u1=wh/(phm*Si); Qi=wh*cphm*(th1-th20); Ai=pai*di*L*N;/*面积的计算应该怎么样？？？？？*/

Rei=(di*u1*phm)/N1; Pri=(cphm*N1)/rd1; Nui=0.023*pow(Rei,0.8)*pow(Pri,0.33); hi0=Nui*rd1/di;

twi=Tmh-Qi/(hi0*Ai);/*壁温的设计*/ Nwi=niandu1(twi); hi=hi0*pow((N1/Nwi),0.14); twi1=Tmh-Qi/(hi*Ai);

for(n=0;fabs(twi-twi1)>=0.5;n++) {twi=twi1; Nwi=niandu1(twi); hi=hi0*pow((N1/Nwi),0.14); twi1=Tmh-Qi/(hi*Ai); }; Twi=twi; Hi=hi; printf("Twi=%f,Hi=%f\n",Twi,Hi); printf("n=%d",n);

/*管外表面传热系数的计算*/

u2=wc/(As*pcm); Qo=wc*cpcm*(tc20-tc1); Ao=pai*d0*L*N; de=4*As/(N*pai*d0); Reo=(de*u2*pcm)/N2; Pro=(cpcm*N2)/rd2; Nuo=0.36*pow(Reo,0.55)*pow(Pro,0.333); ho0=Nuo*rd2/de;

two=Tmc-Qo/(ho0*Ao); Nwo=niandu2(two); ho=ho0*pow((N2/Nwo),0.14); two1=Tmc-Qo/(ho*Ao);

for(m=0;fabs(two-two1)>=0.5;m++) {two=two1; Nwo=niandu2(two); ho=ho0*pow((N2/Nwo),0.14); two1=Tmc-Qo/(ho*Ao); }; Two=two; Ho=ho; printf("Two=f%,Ho=f%\n",Two,Ho); printf("m=%d",m); }

/*求综合传热系数*/ k=(1/Hi+Ri)*Ao/Ai+1/Ho+Ro; H=1/k; printf("H=%f\n",H);

/*指定循环的依据*/ Cmin=min((wh*cphm),(wc*cpcm)); Cmax=max((wh*cphm),(wc*cpcm));NTU=H*A*Cmin; R=Cmin/Cmax;

TT=NTU*sqrt(1+R*R); v=sqrt(1+R); p=(1+exp(-TT))/(1-exp(TT)); e=2/((1+R)+v*(p)); tc2=tc1+e*(th1-tc1); th2=th1-(wc*cpcm)*(tc2-tc1)/(wh*cphm); printf("tc2=%f,th2=%f,H=%f",tc2,th2,H);

printf("The answer is:\n"); printf("tc2=%f,th2=%f,H=%f",tc2,th2,H);

/*换热效率和热阻的计算*/

eh=(th1-th2)/(th1-tc1);/*换热是效率*/

if(Rei<100000) fi=0.4513*pow(Rei,-0.2663); else fi=0.2864*pow(Rei,-0.2258); dph=(fi*L/di+8)*wh*2*1.5/(2*1000*phm);

if(Reo<150)fo=120*pow(Reo,-0.993); else{ if(Reo>1500)fo=0.7664*pow(Reo,-0.0854); else fo=10*(15.312/(pow(log(Reo),4.735))-0.44); }; dpc=(D*(19+1)*fi*0.15/de+10)*wc/(2*1000*pcm);

printf("eh=f%,dph=f%,dpc=f%\n",eh,dph,dpc);

}