Fast Format Function of Float Numbers for LS-DYNA Input Files

formatFloatForLSDYNA.java

    private static String formatFloat10(double d){
        char[] c = new char[10];
        double a;

        if(d == 0.0){
            return " 0.0000000";
        }
        if(d < 0){
            c[0] = '-';
            a = -d;
        }else{
            c[0] = ' ';
            a = d;
        }
        int m = (int)Math.floor(Math.log10(a));

        if(m <= -100){
            for(int i = 1; i < 1 - m; i++) a *= 10;
            c[1] = (char)('0' + Math.floor(a));
            a = (a - Math.floor(a)) * 10;
            c[2] = '.';
            for(int i = 3; i < 5; i++){
                /*c[i] = (char)('0' + Math.floor(a));
                a = (a - Math.floor(a)) * 10;*/
                double b = Math.floor(a);
                c[i] = (char)('0' + b);
                a = (a - b) * 10.0;
            }
            c[5] = 'e';
            c[6] = '-';
            c[7] = (char)('0' + (-m) * 0.01);
            c[8] = (char)('0' + (-m * 0.1) % 10);
            c[9] = (char)('0' + (-m) % 10);

        }else if(m <= -10){
            for(int i = 1; i < 1 - m; i++) a *= 10;
            c[1] = (char)('0' + Math.floor(a));
            a = (a - Math.floor(a)) * 10;
            c[2] = '.';
            for(int i = 3; i < 6; i++){
                double b = Math.floor(a);
                c[i] = (char)('0' + b);
                a = (a - b) * 10.0;
            }
            c[6] = 'e';
            c[7] = '-';
            c[8] = (char)('0' + (-m) * 0.1);
            c[9] = (char)('0' + (-m) % 10);

        }else if(m <= -4){
            for(int i = 1; i < 1 - m; i++) a *= 10;
            c[1] = (char)('0' + Math.floor(a));
            a = (a - Math.floor(a)) * 10;
            c[2] = '.';
            for(int i = 3; i < 7; i++){
                double b = Math.floor(a);
                c[i] = (char)('0' + b);
                a = (a - b) * 10.0;
            }
            c[7] = 'e';
            c[8] = '-';
            c[9] = (char)('0' - m);

        }else if(m <= -1){
            c[1] = '0';
            c[2] = '.';
            a *= 10;
            for(int i = 3; i < 10; i++){
                double b = Math.floor(a);
                c[i] = (char)('0' + b);
                a = (a - b) * 10.0;
            }

        }else if(m <= 6){
            for(int i = 1; i < m + 1; i++) a *= 0.1;
            for(int i = 1; i < 10; i++){
                double b = Math.floor(a);
                c[i] = (char)('0' + b);
                a = (a - b) * 10.0;
                if(i == m + 1){
                    c[++i] = '.';
                }
            }
        }else if(m <= 9){
            for(int i = 1; i < m + 1; i++) a *= 0.1;
            c[1] = (char)('0' + Math.floor(a));
            a = (a - Math.floor(a)) * 10;
            c[2] = '.';
            for(int i = 3; i < 8; i++){
                double b = Math.floor(a);
                c[i] = (char)('0' + b);
                a = (a - b) * 10.0;
            }
            c[8] = 'e';
            c[9] = (char)('0' + m);

        }else if(m <= 99){
            for(int i = 1; i < m + 1; i++) a *= 0.1;
            c[1] = (char)('0' + Math.floor(a));
            a = (a - Math.floor(a)) * 10;
            c[2] = '.';
            for(int i = 3; i < 7; i++){
                double b = Math.floor(a);
                c[i] = (char)('0' + b);
                a = (a - b) * 10.0;
            }
            c[7] = 'e';
            c[8] = (char)('0' + m * 0.1);
            c[9] = (char)('0' + m % 10);

        }else{
            for(int i = 1; i < m + 1; i++) a *= 0.1;
            c[1] = (char)('0' + Math.floor(a));
            a = (a - Math.floor(a)) * 10;
            c[2] = '.';
            for(int i = 3; i < 6; i++){
                double b = Math.floor(a);
                c[i] = (char)('0' + b);
                a = (a - b) * 10.0;
            }
            c[6] = 'e';
            c[7] = (char)('0' + m * 0.01);
            c[8] = (char)('0' + (m * 0.1) % 10);
            c[9] = (char)('0' + m % 10);

        }

        return new String(c);
    }