c++ - Polynomial Class: Polynomial Multiplication -

-

i have polynomial class has get_vect member function stores integers in vector representation of coefficients of polynomial. now, trying multiply 2 polynomials using multiply non-member function, stuck when comes actual multiplication of vectors. far, have shown below:

polynomial multiply(const polynomial & poly1, const polynomial & poly2) {     vector<int> poly1 = poly1.get_vect();     vector<int> poly2 = poly2.get_vect();     vector<int> poly3;      if( poly1.size() < poly2.size() )     {         for(size_t = 0 ; poly2.size()-poly1.size() ; ++i )         {             poly2.push_back(0);         }     }     else if( poly1.size() > poly2.size() )     {         for(size_t = 0 ; poly1.size()-poly2.size() ; ++i )         {             poly1.push_back(0);         }     }      return poly3; }

i see how has follow below pattern:

enter image description here

ok, if understand problem correctly, want poly3 vector<int> holds coefficients result polynomial multiplication between polynomials represented poly1 , poly2.

tacit in request 3 polynomials polynomials in single variable, each coefficient representing coefficient in front of increasing power of variable. ie. { 4, 5, 6, 7 } corresponds 4 + 5x + 6x2 + 7x3.

if so, actual multiplication shouldn't difficult @ all, long polynomials aren't terribly huge. need code looks approximately this:

    poly3.resize(poly1.size() + poly2.size() - 1, 0);  // make output big enough; init 0      (size_t = 0; != poly1.size(); i++)         (size_t j = 0; j != poly2.size(); j++)             poly3[i+j] += poly1[i] * poly2[j];

now result in poly3 should product of poly1 , poly2.

it's entirely possible forgot edge condition; i'll watch comments here point out did. in meantime, though, did few tests , appears gives correct output.

if have rather large polynomials, might want math libraries handle multiplication. under 20 - 30 terms? unless code leans hard on polynomial evaluation, suspect won't bottleneck.


Comments

Post a Comment

Popular posts from this blog

css - Which browser returns the correct result for getBoundingClientRect of an SVG element? -

-
this svg contains rect overflows svg element: <svg id='svg' width='10' height='10'> <rect x='-10' y='-10' width='30' height='30'/> </svg> chrome 28 , opera 12 return getboundingclientrect() svg element width , height of 10. firefox 23 reports width , height of 30. correct? jsfiddle the relevant spec cssom , delegates svg spec if svg element not "have associated css layout box". haven't found definition of "having associated css layout box", correct result seem hinge on definition, getbbox returns 30x30 rect in browsers. this firefox bug fixed now, fix in firefox nightlies , should make through firefox 33 released on 14 october 2014. see bug 530985 details.
Read more

gcc - Calling fftR4() in c from assembly -

-
i trying asm fft implementation www.embeddedsignals.com work. running make gives error: undefined reference fftr4(short*, short*, int) at top of asm have .syntax unified .thumb .global fftr4 .type fftr4, %function and there #define's associate c functions arguments registers followed macros fftr4 function uses. after that, fftr4 called .thumb_func fftr4: stmfd sp!, {r4-r11, lr} mov tmp0, #0 // bit reversed counter mov tmp1, #0 .word 0xf3a2fa92 //rbit r3,r2 //rbit r,n lsl r,#3 and c code follows: void fftr4(short *y, short *x, int n); short x[512]; short y[512]; int i; void loop() { (i=0;i<512;i++) x[i]=0; (i=0;i<512;i=i+8) { x[i+0]=16384; x[i+2]=16384; x[i+4]=-16384; x[i+6]=-16384;} fftr4(y, x, 256); serialusb.println(y[128]); serialusb.println(y[129]); serialusb.println(y[384]); serialusb.println(y[385]); // expected results: //y[128]is 8191; y[129] -8190 y[...
Read more

.htaccess - Matching full URL in RewriteCond -

-
i'm trying block post access site (and return 403), except 2 ip's , 1 url ( http://mydomain.com/about-us/contact-us/ ). here's have: rewritecond %{request_method} post rewritecond %{remote_addr} !=1.2.3.4 rewritecond %{remote_addr} !=4.3.2.1 rewritecond %{request_uri} !^http://mydomain.com/about-us/contact-us/$ rewriterule ^ / [f] these rules allowing access ip properly, contact page still not accessible. i'm not sure i'm using request_uri correctly? i've tried variations relative urls rewritecond %{request_uri} !^/about-us/contact-us$ , rewritecond %{request_uri} !^/about-us/contact-us/$ without luck. what doing wrong please? it looks me rule on file name specific. if relax bit, should work. made few other esthetic tweaks. give try: rewritecond %{request_method} post rewritecond %{remote_addr} !^1.2.3.4 rewritecond %{remote_addr} !^4.3.2.1 rewritecond %{request_uri} !about-us/contact-us rewriterule ^ - [f]
Read more