/* * Justice Unlimited Resistor calculator * * Copyrigh (C) 2004, Nathan (Acorn) Pooley * * * */ /* * *@DOC@ calculate resistor values * */ #include #include #include #include double rval[] = { 1.0,1.2,1.5,3.0,3.3,3.9,4.3,4.7,5.1,5.6,6.8,7.5,8.2,9.1, 10.0,12.0,15.0,30.0,33.0,39.0,43.0,47.0,51.0,56.0,68.0,75.0,82.0,91.0, 100.0,120.0,150.0,300.0,330.0,390.0,430.0,470.0,510.0,560.0,680.0,750.0,820.0,910.0, 1000.0,1200.0,1500.0,3000.0,3300.0,3900.0,4300.0,4700.0,5100.0,5600.0,6800.0,7500.0,8200.0,9100.0, 10000.0,12000.0,15000.0,30000.0,33000.0,39000.0,43000.0,47000.0,51000.0,56000.0,68000.0,75000.0,82000.0,91000.0, 100000.0,120000.0,150000.0,300000.0,330000.0,390000.0,430000.0,470000.0,510000.0,560000.0,680000.0,750000.0,820000.0,910000.0, }; double rtry(double target, double *best, double *best_val, double r1, double r2, double r3) { double r; if (r2 && r3) { r = 1.0 / ((1.0 / r1) + (1.0 / r2) + (1.0 / r3)); } else if (r2) { r = 1.0 / ((1.0 / r1) + (1.0 / r2)); } else { r = r1; } if (r < target) return r; // only round up if (best) { double err = target - r; if (err < 0.0) err = -err; if (err < best_val[1]) { best_val[0] = r; best_val[1] = err; best[0] = r1; best[1] = r2; best[2] = r3; } } return r; } void rcalc(int val, int c) { int cnt = sizeof(rval)/sizeof(rval[0]); double best3[3] = { 1000.0, 0.0, 0.0 }; double best3_val[2] = { 1000.0, 1000.0 }; double best2[3] = { 1000.0, 0.0, 0.0 }; double best2_val[2] = { 1000.0, 1000.0 }; double best1[3] = { 1000.0, 0.0, 0.0 }; double best1_val[2] = { 1000.0, 1000.0 }; int i,j,k; double target = (double) (val); double r; if (val < 100) { cnt = (cnt * 2)/5; } else if (val < 1000) { cnt = (cnt * 3)/5; } else if (val < 1000) { cnt = (cnt * 4)/5; } for (i=cnt; i--; ) { double r1 = rval[i]; r = rtry(target, best1, best1_val, r1, 0.0, 0.0); //if (r < target) break; for (j=cnt; j--; ) { double r2 = rval[j]; r = rtry(target, best2, best2_val, r1, r2, 0.0); //if (r < target) break; for (k=cnt; k--; ) { double r3 = rval[k]; r = rtry(target, best3, best3_val, r1, r2, r3); //if (r < target) break; } } } printf(" '%c' %2d r=%6.2f r1=%5.1f\n", c,val,best1_val[0], best1[0]); if (best2_val[1] < best1_val[1]) { printf(" '%c' %2d r=%6.2f r1=%5.1f r2=%5.1f\n", c,val,best2_val[0], best2[0], best2[1]); } if (best3_val[1] < best1_val[1] && best3_val[1] < best2_val[1]) { printf(" '%c' %2d r=%6.2f r1=%5.1f r2=%5.1f r3=%5.1f\n", c,val,best3_val[0], best3[0], best3[1], best3[2]); } printf("\n"); } int main(int argc, char *argv[]) { int c; int num = 0; int isnum = 1; int i; for (i=0; i<8; i++) { c = getc(stdin); if (c == EOF) break; } printf("Content-type: text/html\n\n"); printf("\n"); if (c == '=') { printf("

\n");
        printf("r1, r2, and r3 in parallel are equivalent to r\n\n");
        printf("Column 1 is the character\n");
        printf("Column 2 is the target value\n");
        printf("Column 3 is the actual resistance value\n");
        printf("Column 4-6 are the resistors that make up that value\n\n");
        printf("Each character is tried 3 times - for 1, 2, and 3 resistors\n\n");
	
        while(1) {
            c = tolower(getc(stdin));
            if (c==EOF) break;
            if (isalpha(c)) {
                rcalc(c-'a'+1,c);
            } else if (isdigit(c)) {
                rcalc(c-'0'+27,c);
                rcalc(c-'0',c);
                if (isnum) {
                    isnum = 2;
                    num *= 10;
                    num += c-'0';
                }
            } else if (isspace(c) || c=='+') {
            } else {
                isnum = 0;
                printf("%c = ???\n\n",c);
            }
        }
        if (isnum == 2) {
           printf("\n\n\nTHE NUMBER %d\n",num);
    	   rcalc(num,'?');
        }
    	printf("\n\n

\n"); } printf("

\n"); printf("

\n"); return 0; }

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